If you need the odd hand here and there, I'm happy to help.
Here's a preview of most of the units for Japan to prove I'm hard at work:


Okay, I guess that makes sense, but I'd still reconsider it since it hasn't looked like that in a while and will undoubtedly cause confusion to others as well.
IIRC the stars on the EU flag also represent the member states, so I guess they just copied since the meaning is somewhat established already.
Actually the stars on the flag used by the EU have nothing to do with the member states, it is in fact the flag of Europe as adopted by the Council of Europe. Here is a short description of what the falg is all about.
@ Dark Jedi something like this would probably be better for use as the Persian symbol (obviously without the numbers), as it was traditionally used to signify the divinely royal person of the Persian monarch (who himself symbolised the state).
Also on Portugal may I suggest (to get rid of the green you're complaining about) to revert the colours back to white and blue. Here is a link with the historical Portugese flags.
On the celtic design, mabybe a bit more intricate on the knot. Not quite this level, but that is fairly average for Celtic artwork.
Looking very good so far by the way.
I will also look into using an older version of the Portuguese flag. Thank you for your comments. 
Actually the stars on the flag used by the EU have nothing to do with the member states, it is in fact the flag of Europe as adopted by the Council of Europe. Here is a short description of what the flalg is all about.

Ask the Council of Europe.![]()
I should be updating the F&CC mod soon with some changed flags and a more diverse color set...
I really enjoy piecing together the best that the community has to offer. So far I have several nearly complete sets: Japan, Germany, Russia and England with work starting on France. Where the art is available I'm also doing different unit art across eras...for example; swordsman, axeman, archers, etc. more resemble longbowman, knights, etc. in the Medieval, and Rifleman look more like WWI infantry in the Industrial. Perhaps more screenshots will follow soon. 

Well unless someone can point me in the direction of a mod that allows flags to change per era or technological period, the United States is sticking with the 13 stars.![]()