-Plane Doctrine, they don't give their supposed bonuses to all planes (perhaps many other doctrines don't work as well), and Japanese planes don't benefit at all from air doctrine. Mostly doctrines in general need work (most of them don't even work)
-Japan mission to capture Guadal Canal airport is bugged, when Japan captures the Airport, units don't spawn at Guadal canal. (noticed that most of japan missions are quite bugged) (and perhaps other nation missions)
-"Tribute building" are quite weird and buggy, maybe the cities sometimes function when you tribute them though the Factory doesn't work (atleast from my experience) (also maybe put tribute for docks too?) (also add the tribute capital option when an ally captures your capital)
-Tank Factory hotkey not working.
-The plane bug where your fighters can't shoot bombers after they dropped their bombs is very annoying and game breaking.
-Jap Engies can still shoot ships,
Mountain climbing and river crossing bugs (I'm just gonna point out the location or the region)
-Scandinavia: Norway (Oslo, Bergen) and center Scandinavia (minor)
-Asia: Himalaya mountains (extreme mountain climbing tanks)
-America: river crossing (between the two bridged cities, can be exploited for better creeping of those "two bridged" cities)
-Visual bug for Zis truck displaying soviet troops even if it is Axis.
-Flamethrower model, when doing an animation it skeleton appears, or when sometimes shooting same thing happens.
-US/UK Half-Track model when shooting sometimes appears to be shooting like a "Mobile Flak"
-Perhaps for Axis Engineers should say they also construct "V2" rockets
Also check Voting sistem, since It was quite buggy last time I played (chose Historical and Domination, it said Alliance set to "domination" and gave FFA and Domination modes)
Note that those "may" not be all the bugs, I will try to find more later this day, though for now I'm quite busy, wish you good luck at making this version great.
Just passing by...