Alright, so I'll attempt to list here all of the bugs that me and others have found. If I've missed a bug, please tell me. This list is massively incomplete.
Save bug - Sometimes, for unknown reasons, save files get corrupted and crash the game when clicking load game. There is no fix for this other than to delete your save files. This can happen on games under 100 turns, but it is more common on 100 and above games.
Overflow bug - Sometimes, when a variable gets too high or too low, it overflows and goes into the negatives and gets stuck there. This is the reason for all of the permanent 99 economy provinces. There is no fix for this other than to start a new save. It can also happen with population and (very rarely) economy. A fix for the 99 province economy is to reduce the province pop. to less than 10,000, using recruit.
AI decision making (Umbrella term) - The AI decision making is broken. It will NEVER accept a trade request for one of their provinces, and will always accept any war request, as long as nothing else is bundled in. Forming unions is also broken to an extent. It works fine with coalitions and non-aggression pacts, but not with defensive pacts. It also waits about 40 turns until it forms a civ.
"Game crash while loading" - Sometimes, the game does what the bug says.
Conscript + Req bug - If you conscript a army first, then recruit, the recruit will recruit the same amount of soldiers as the conscript. This does not work the other way.
Terrain types crash - If you add or edit a terrain type, the game crashes when exiting the terrain menu. There is presently no fix for this of which I am aware.
Flickering cursor - Sometimes the game does not launch. The only visible thing is that your cursor will flicker randomly for 1-10 seconds. This is only on PC. The problem here is either invalid drivers or a unsupported GPU. It could also be caused by not enough RAM.
Game not launching on Android - Sometimes the game simply doesn't launch. This is not fixable, and is usually caused by insufficient RAM.
Game instantly crashes after loading - This is caused either by game file tampering, mod problems, or invalid province data. Validate your steam files to fix this issue.
Android blackscreen bug (I don't know how to fix this)
On Android, sometimes music doesn't play correctly
August is after September (no idea why)
On Android and PC, when you win a game, nothing appears and in some cases the game crashes. Fix by validating your steam files, and if that doesn't work, uninstall and reinstall. If you have a GOG install, then do the same thing, except run the GOG launcher as administrator. On Android, try uninstalling and reinstalling.
Sometimes the AI will form a civ that makes no sense (E.G. Nazi Germany)
On Android, there is no create city or create leader function
Leaders live forever, which is very broken. This happens across all platforms and there is no fix.
General map errors (E.G. Alaska's borders being fixed in the US states scenario but being broken in the modern world)
On Android, when a tribal civ conquers a province, they may start gaining 0.4 tech per turn. Fix this by reinstalling.
Please help by adding to this list.
Roman Empire should have more land in Africa
Palatinate should be an elector.
Palatinate should be an elector.
Borders of Austria are slightly off (It should have one of Hungary's provinces)
The Byzantine Empire should be weaker (The Ottomans should have one of the Greek provinces)
Menjiang and Manchukuo should be vassals of the Empire of Japan
Dominion of Canada should be a puppet of the United Kingdom
Japan should hate the Chinese warlord states
Yunnan's border with China (F) is slightly off
Sierra Leone's capital is Freetown.
French Guinea should be a vassal of France
The Isle of Man, the Falklands, South Georgia and the South Sandwich Islands, and other associated Crown dependencies should be vassals of the United Kingdom
Iran is not a democracy - It would best fit into the Monarchy category
Rename Swaziland to Eswatini
Swaziland/Eswatini is a monarchy, also please fix the flag.
Crimea is shown as being controlled by Ukraine (Russia is in control of it currently)
Alaska's borders stretch into Canada way too far
509 BC-29 May 1453