Having played the four main western European civs (England, France, Burgundy and Germany) quite a lot, I think that area of the map needs a bit of balance, particularly to give Burgundy a bit of a leg up and increase the late game challenge for human France. At the moment:
If human France gets its 1st UHV, after Burgundy and Germany spawn it will end up with around ten cities (Paris, Tours, Bordeuax, Toulouse, Barcelona, Milan, Florence, Langres, Aix-La-Chapelle and Osnabruck in my game and potentially also Calais / Dunkerque). Burgundy will spawn with three cities, assuming Marseille doesn't get barb razed, and Germany will spawn with three (two settlers plus Ausburg). This, imo, makes human France very OP and easily able to crush Burgundy and get the next two UHVs without serious competition.
Also, human Germany has to found a city in Bavaria, which will be in a poor location and crushed between Ausburg, Prague and Austria's flip zone. Finally, human France has little incentive to settle Normandy, so AI England will start off very weak, and AI France will often settle Normandy in a poor location like Liseux or Cherbourg, thus making England very difficult to play.
My proposed solutions to this would be:
1. Extend Bavaria to include Ausburg and add independent Strasbourg west of the Rhine, 1SW of the honey, in Swabia. Defended by one archer.
2. Extend Burgundy's flip zone to include Strasbourg and also Champagne, with the exception of Paris's BFC.
3. Extend Germany's flip zone to include all of Saxony and Lorraine, to make sure AI Germany flips the human French cities in these regions.
4. Add Caen as an independent city spawning in Normandy in 965AD to represent the Duchy of Normandy (where William the Conqueror originated from). Remove Normandy from the AI French settler map.
5. Add Nantes as an independent city in Bretagne to reflect its historical importance as part of the March de Bretagne.
6. Give Marseille an extra defender to try and stop it being razed by the barbs so often.
7. Add Milan and Florence to the AI Burgundian flip zone if they are controlled by human France. I think this should be possible, as DoC has different flip zones for human and AI players.
The aim of this is to better reflect the outcome of the Treaty of Verdun and balance the region:
Whilst it's not an exact representation (with Dijon being Burgundian and Lorraine being German), it will provide more balance than we have right now.
In terms of the playability of the four civs:
For the 1st UHV, France should need to conquer Bavaria (Ausburg) as well Swabia (Strasbourg). This will better reflect Charlemagne's empire, and Strasbourg should be an easy first target to capture, so the extra city won't make the UHV too challenging.
After the 1st UHV, instead of human France being completely dominant, it will be left with Paris, Tours, Bordeaux, Toulouse, Barcelona and potentially Calais / Dunkerque and Nantes. This change should in fact help encourage the French player to build in Picardy, as they will need the extra city once their empire is split. Burgundy will have Dijon, Strasbourg, Lyon, Marseille, Milan, Florence, and Langres, so won't be such a pushover for France any more. Germany will also have more power with Aix, Osnabruck, Frankfurt, Ausburg and another city from the spare settler, so they will be another major opponent for France in the future.
Human Burgundy will flip an extra city in Strasbourg, which will put them on a comparable footing with the French and Germans. It will also create more border tension with the Germans, potentially creating more conflict. As a result of Burgundy's superior starting situation, the third UHV might need to be changed to be more challenging that just having a higher score than the other three. AI France doesn't usually manage to settle Champagne, so this won't give Burgundy another extra city.
Human Germany will start roughly the same, as AI France won't usually found cities in Saxony or Lorraine. However, Germany will have a bit more of an interesting challenge, as rather than having to found a relatively useless city in Bavaria right before the deadline, they will have to go to war with Burgundy to capture Strasbourg.
Human England will get a better city in Europe, and probably have to fight a stronger France, as AI France will usually capture Nantes relatively early, thus being stronger when England spawns. A stronger Burgundy will also be a stronger rival for England to fight once France has been dealt with.
If human France gets its 1st UHV, after Burgundy and Germany spawn it will end up with around ten cities (Paris, Tours, Bordeuax, Toulouse, Barcelona, Milan, Florence, Langres, Aix-La-Chapelle and Osnabruck in my game and potentially also Calais / Dunkerque). Burgundy will spawn with three cities, assuming Marseille doesn't get barb razed, and Germany will spawn with three (two settlers plus Ausburg). This, imo, makes human France very OP and easily able to crush Burgundy and get the next two UHVs without serious competition.
Also, human Germany has to found a city in Bavaria, which will be in a poor location and crushed between Ausburg, Prague and Austria's flip zone. Finally, human France has little incentive to settle Normandy, so AI England will start off very weak, and AI France will often settle Normandy in a poor location like Liseux or Cherbourg, thus making England very difficult to play.
My proposed solutions to this would be:
1. Extend Bavaria to include Ausburg and add independent Strasbourg west of the Rhine, 1SW of the honey, in Swabia. Defended by one archer.
2. Extend Burgundy's flip zone to include Strasbourg and also Champagne, with the exception of Paris's BFC.
3. Extend Germany's flip zone to include all of Saxony and Lorraine, to make sure AI Germany flips the human French cities in these regions.
4. Add Caen as an independent city spawning in Normandy in 965AD to represent the Duchy of Normandy (where William the Conqueror originated from). Remove Normandy from the AI French settler map.
5. Add Nantes as an independent city in Bretagne to reflect its historical importance as part of the March de Bretagne.
6. Give Marseille an extra defender to try and stop it being razed by the barbs so often.
7. Add Milan and Florence to the AI Burgundian flip zone if they are controlled by human France. I think this should be possible, as DoC has different flip zones for human and AI players.
The aim of this is to better reflect the outcome of the Treaty of Verdun and balance the region:

Whilst it's not an exact representation (with Dijon being Burgundian and Lorraine being German), it will provide more balance than we have right now.
In terms of the playability of the four civs:
For the 1st UHV, France should need to conquer Bavaria (Ausburg) as well Swabia (Strasbourg). This will better reflect Charlemagne's empire, and Strasbourg should be an easy first target to capture, so the extra city won't make the UHV too challenging.
After the 1st UHV, instead of human France being completely dominant, it will be left with Paris, Tours, Bordeaux, Toulouse, Barcelona and potentially Calais / Dunkerque and Nantes. This change should in fact help encourage the French player to build in Picardy, as they will need the extra city once their empire is split. Burgundy will have Dijon, Strasbourg, Lyon, Marseille, Milan, Florence, and Langres, so won't be such a pushover for France any more. Germany will also have more power with Aix, Osnabruck, Frankfurt, Ausburg and another city from the spare settler, so they will be another major opponent for France in the future.
Human Burgundy will flip an extra city in Strasbourg, which will put them on a comparable footing with the French and Germans. It will also create more border tension with the Germans, potentially creating more conflict. As a result of Burgundy's superior starting situation, the third UHV might need to be changed to be more challenging that just having a higher score than the other three. AI France doesn't usually manage to settle Champagne, so this won't give Burgundy another extra city.
Human Germany will start roughly the same, as AI France won't usually found cities in Saxony or Lorraine. However, Germany will have a bit more of an interesting challenge, as rather than having to found a relatively useless city in Bavaria right before the deadline, they will have to go to war with Burgundy to capture Strasbourg.
Human England will get a better city in Europe, and probably have to fight a stronger France, as AI France will usually capture Nantes relatively early, thus being stronger when England spawns. A stronger Burgundy will also be a stronger rival for England to fight once France has been dealt with.