For some reason, even though I always click 'Player Only', it still gives the decision to some other countries. Same with the super modifier mod.

I've received similar bug reports from other people on other mods that use the same Player Only option event, so odds are something is broken. However, I can't seem to recreate the bug, even though I've tested it many times.
This mod is supposed to be compatible with anything, but just in case, are you running any other mods that might be interferring?

well the only one that comes to my mind right now is the ck2 assassination plot mod

Can you send me a link?

http://steamproxy.net/sharedfiles/filedetails/?id=1292122612

So, in my game the decision just doesnt exist. is there an alternate download maybe?

No, this mod is only on the Steam Workshop, not that downloading it from a different place would change much. If the mod is showing up in your mods list and you activated it, then the issue must be in the game somewhere.
Are you sure the decision is possible? Sometimes the decision will disappear if all of your provinces are already the same culture, and will reappear when you annex new territory of a different culture.
Also, are you running any other mods with this one? It's possible that the issue could be a mod conflict.