I've been playing quite a bit of WoE2 lately and have some thoughts for tweaks that can improve the game:
-starting positions: they seem rather grouped. Starting on a M world map a bunch of times, nobody ever seemed to spawn in Africa. Could they be spread out a bit more?
-the AI is rather bad, on the harder levels/bigger maps, let the AI start with some extra units and/or techs. So e.g. map size VS-1settler+1scout, S-1settler,2scout, M-2settler,2scout, B-3settler,3scout. Difficulty: +1 tech per AI per higher level
-additional to that: the AI is horrible at finding a good spot to settle. I am building a small tool in Excel to help calculate good settlement spots, could that help you?
-To help map development: can you open the specs for map files?
-barbarians: it's really easy to kill them once you have e.g. spearmen, maybe increase their camp strenght and type of units they create once every civ has passed a certain tech?
-seaside cities seem to grow a lot bigger than landbased cities, that feels off, e.g. adding +1food to farms after the invention of fertilizer can balance that a bit.
-AI improvement: please do check out c-evo.org. It's an old open civ project, has an open AI framework with open code and quite some people have built rather good (competitive) AIs for it.