You should be able to get achievements just using recifense's table. however if you want to access the console in an ironman game you need compactdisc's extension.
there are other things that could prevent you from getting achievements:
- playing with mods that change the checksum. only for ck2 there has been found a way around that so far, both eu4 and stellaris you are limited to vanilla game experiences.
- occasional a patch will for no reason whatsoever make your savegames no longer elligible for achievements. in my experience stellaris is very prone to that. if you are going after specific achievements try to make sure to stay within a single game version.