Never bother apologize for disagreeing with me, the Capo, I find disagreement much more fun, if I didn't want people to disagree with me I would have never put up Spain and Portagul's ancient sets for discussion. For example, Spain's middle ages set will be during the time of El Cid and I'll make those units regardless of what anyone thinks

.
Anyway,
First I disagree with you about the Iberian Celts being the same as Gallic Celts. Since you requested Gallic style units for the Celtic civ, I would not really feel that bad to have both Gallic and Iberian Celtic units in the game. Indeed, there was probably just as much difference between France and England during the middle ages then between Iberian and Gallic Celts. Which is one of the reasons why I dislike the idea of a "Celtic" civ. What's next? A "Turkish civ" to represent everything from central Asian nomads to Ottomans? If civilizations where supposed to be this generic, then why the divide of civilizations on a national level such as Germany, France, England .etc?
But I digress.
Also the Visigoths are Germanic and I'm a bit tired of making Germanic style troops at the moment. All of the invading Germanic tribes have similar armor and dress to each other which becomes very dull after a awhile.
As I was planning,
France - Germanic tribes.
Germany - Germanic tribes!
Holy Roman Empire - Germanics tribes again!,
Netherlands - you guessed it, Germanic tribes!!
As for the rest of Europe,
Celtics - Celtic, Gallic to be specific.
British - Roman-British,
Portugal - Iberian-Celtic,
Spanish - Iberians (Finally something relatively unique).
And good ol' Russia is the only Slavic civ so it gets those flavor units all to itself!
Oh wait, I promised I would make some Polish units... So Russia will just have to share that culture.
To tell you the truth, the problem with the over abundance of European civs and flavor units is the overlap is ridiculous. Especially if you try to trace a culture back in time. I could create simply fictional middle ages style ancient units, however, Danrell has already did this. If you think vanilla is bad enough, I once planned to make a good ancient/classical/dark age/middle ages mod. Let's try thinking up flavor units for all of those eras

.
About the comment about Celtic-Iberians being a Spanish civs ancient age being the same as having native Amerindians as a ancient units for America. Do you have any sources for there being any "major" population change do to the Visigoths, etc all of the native Spanish were mostly wiped out do to plague and resettlement by Visigoths? I hate to bring up this topic dealing with the ancestry of many European tribes and peoples as all of the sources I have read on this topic have been bias to say the lest, but I doubt that the Visigoths replaced the native Spanish population. It is more likely that they became the rulers or aristocracy in the Spanish area just as the decedents of Frankish people became the main nobles in France and Germany (such as Charlemagne) or the Mongols and Manchurians became the ruling class when they conquered China. Over time they would have probably intermarried with the local population, however this is "very" different from the relationship between native Americans and the European settlers.
However you do have a point, and I may make Visigoths one day as a alternative set (which I will end up using for my mod anyway). However, I will probably still make the Iberians and Celtic-Iberians first.
Edit: Oh, I forgot to answer your question about the Phoenician units. It depends on what type of Phoenician units that you want, a Phoenician civ is as generic as a Celtic civ, if not more so. Everything from Tyre to Carthage could be used as a example as a Phoenician civ and I've never saw any good pictures of a Phoenician army other then Carthage. I think Tyre (or other Phoenician cities) armies probably would have look similar to the armies of the surrounding area. Given that not much is known about the "biblical times" in the near east outside of Egypt you could look at popular pictures of Hebrew and Philistine armies to get a idea of what they could have looked like or you could just keep using your units that you made before.
Here is a picture of a Phoenician coin which could be of Phoenician warriors on a boat.
http://en.wikipedia.org/wiki/File:PhoenicianCoin2A.jpg