This isn't neccasarilly a bug but the chaos mana "benefit" where your units start out mutated is a real pain, I had 2 archers in a row start out with mutated(-15, -20 strength -45 and -5 heal rate and a small amount of first strike chances 2-3 I think?). Im hoping this isn't one of the things your keeping?
Oh and a few bugs....exploring the island world improvement; the explore button is randomly nonfunctional the first couple times you press it, werewolves only have access to a "skip promotion for this level" promo(even after becoming bloodied, which was annoying after I spent my gold upgrading a turned adept unit. And finally why don't the svartalfar have a better unit than illusionist, if I wanted to weaken a unit and then put my mage at risk(number gen hates me) I'd use a catapult.
Clan of Embers

this is a long one)-fort commanders can only get promos for leading units, ie no stronger attack etc which was a big hit as my unpromoted assasin easily shanked him in his fort in my svartalfar game. Fort Commanders have no movement:which is much less effective than the cannot move function for most fort units as they can mobility or haste and just wander off and it makes it much more tedious when you have to check every fort to see if your commander has gained a level. The overflow mechanic is just a waste of a trait flatout:my capital with buildings produces about 130 hammers a turn, and if you do the math you can't really build any extra units a turn with that amount, secondly there seems to be an overflow cap where access production is turned into gold yeah works really well when your trying to save up for that seemingly unachievable multi unit per turn production. It also doesn't work as bulding a soldier of kilmorph(who costs around 60 hammers), I ended up with only one soldier. Similar results with an archer.
The thing to take away from this would be: OVERFLOW IS NOT WORKING/sucks.
oh and the illusion promo on the summoned unit doesn't always restore to max health after combat