Please let me preface this with a resounding
thank you for the effort put forth. The scenario is great and my comments are purely intended as food for thought and brainstorms for enhancements.
I have played the scenario twice, once each with versions 10.5 and 11.2. I have collected a number of comments and comparisons about each. Numbered for reference, not significance.
1) Troop Transports
I loved the troop transport in 10.5, why was it removed in 11.2? One of my favorite tactics was to create an army of flamethrowers, load it onto a transport (because they are non-mechanized), and thrust two extra spaces into enemy territory. Armies of flamethrowers are also nice in a paratroop transport. Another use of the troop transport was to shove the slow Panzer Cracks into a battle. They truly served the intended purpose of letting infantry keep up with a blitzkrieg of tanks.
2) Waffen SS
The Waffen SS in 11.2 is WAY TOO POWERFUL. I saw a recent thread where the poster (as Britain) saw Germany building nothing but SS. I know why this is so. It is too strong, WAY too fast and, when used in an army, is able to reach 30 spaces into enemy territory and then attack in FORCE!! I built almost all of my German armies as purely SS. They only attack three times instead of 5 for panzers, but their range more than makes up for it. I used a platoon of 3-4 SS armies per theater and mopped up. I supported each with a few separate SS and the occasional tank. My 11.2 scenario ended in TOTAL conquest by Sep 1942 that includes taking over all of Russia and even New York/Toronto.
3) Dora Rail Gun
I understand that these units moved on rails and should therefore be fast, but I fear you have modeled them incorrectly. They should be less mobile that other units because they can ONLY go on rails. I think they should have the property set that prevents all movement through any terrain that does not have a road. Like tanks that cannot go through mountains without a road, these guns should not be able to go across even grassland without a road. Since the road in this scenario are really representing railroads I think this would model a rail-only unit correctly. That way if you want them on the eastern from, but the rails have been cut, your workers better get busy.
3b) Dora Rail Guns (part 2)
I dont think these need to be invisible. If a player leaves them undefended, allow them to be attacked. They were not very stealthy due to their bulk (and effects

)and so should not be modeled here as invisible.
4) Mines
I thought the mines were a good idea, but as others have noted they are pretty unusable as is. I think making them movable with a troop transport or paratroop plane would help a lot.
5) Combat Engineers
I did not see any extra value in the combat engineer. They dont work much (any?) faster than workers and their increased range is not a big asset. Giving them an attack value actually lets them rush in a and capture towns (or workers/artillery) that have been left undefended. It seems a little weird that glorified workers would do this. I also used this tactic with the Dora Rail Gun! Can you imagine a rail gun moving into enemy held territory to capture units? Seems silly. I guessed that the attack strength of 1 was to make them die when attacked instead of getting captured. I do think this was a good idea maybe there is another way to implement it like ships and planes that die without fighting back. Another idea what if the combat engineer are the units that can transport mines?
6) Commonwealth Reinforcements
In both versions, when I captured Port Said, I got this wonder and it continued to produce German nationality British Infantry. I hoped for the same from Canadian, US, and Russian Reinforcements, but they were all lost when the cities were captured.
7) Tactics discussions
7a) Oil
Clearly the only resource worth fighting for, but I made a deal with Russia to get Oil in exchange for Mut/Prot and some cash. This allowed an unfettered attack on France and into Rumania to secure my own source. Then I could attack Russia without losing it.
7b) North Africa
In both 10.5 and 11.2 I was able to airlift a significant force to North Africa and use it to sweep to the east. In 10.5, I captured a worker and built another airfield closer to the British cities in Egypt. In 11.2 there is already a nicely located airfield to conquer. From there the British and French oil sources are easily conquered.
7c) Russian Cancer
In 10.5, I loaded a transport with a worker and some military units and sailed to the middle of the black sea. On the next turn, I sailed north to the Russian coast and unloaded (not on the caucuses), but north east of there. On the next turn, Russia demanded that I remove my units, so I did and these units were relocated to a small neutral spot in the center of eastern Russia. I built an airfield and flew every available unit into this field. When the war with Russia started, he had too many places to defend and fell quickly. In 11.2 this was not necessary because of the range of the SS armies I mentioned above.
Sorry for the book length post - I will save some more comments for later. I would love to hear comments on these ideas and tactics.
DaveR.