Replace CK2game.exe in the root folder of the game (for example, "..SteamsteamappscommonCrusader Kings II") so that you can always get achievements with mods and any translation versions without using third-party utilities.

Attention ! Since this exe file is a Steam one, you need to launch the game the same way as always - through Steam!

The game will not distinguish the modified file from the original, it will not affect the checksum of the game (without mods), therefore, it is fully compatible with others (for example, you can play online with other players who have an unchanged file). When you launch games with mods, achievements will be available even if you start the game with save (Ironman), in which achievements were initially disabled, they will still become available.