an idea I had to try and hopefully improve the AI:
the AI understands well things that were in vanilla civ4, but has trouble grasping new concepts. AI flavors ( growth, economy, culture, religion, military, science... ) could be tweaked to be more effective imho. in FFH knowing that something is related to "military" doesn't really mean enough. I think the "military" flavour should be replaced by different flavours depending on the kind of unit/building. so new flavours could be added: Melee, Mounted, Recon, Arcane, Divine, Siege, Archery... then you can easily tell the Hippus "you like Mounted" , the Ljolsalfar "you like Archery" , the Svartalfar "you like Recon" etc. in a way they should easily be able to understand very well. the same concept should apply nicely even to techs, so Hippus should like Mounted techs ( the mounted line ) etc. , and we could have civs with different characters without having to resort to the dreaded beelines that I think we all learned often result in a horrid behaviour ( "umh, bronze working would take 130 turns to research cuz I got no economy whatsoever... but I want it NOW, dammit! research BW already!"

)
another concept could apply nicely to the issue with the AI not grasping very well the concept of needing buildings to produce units: the concept of City Specialization from vanilla civ4. I'm pretty sure the AI knows about it since it's critical to success in the vanilla game. so the AI could think, "ok, I'm going to specialize this city for science, this one for commerce... this one for Recon. hunting lodge is Recon, let's build it. now let's spam hunters"
one last thing, even if the AI understands flavours that were in vanilla quite nicely ( so it knows what culture is, it knows what science is and uses them accordingly ) , some buildings could still use some tweaking, I guess in XML to make the AI realize they are critical while others are less useful. first thing that comes to mind is Inns for example: the AI loves them, and often ignores that Markets and Elder Councils are a lot more effective considering their cheap cost. it is also very very fond of granaries and smokehouses even in cities that have plenty of food and don't need them, for some weird reason only it knows
totally unrelated minor thing: the Amurite leaders right now are set to never ever, ever ever, ever ever trade techs even with their best buddies. not a very smart behaviour, this should be toned down imho.