I can understand what you meanAykis16, however, what I did is I started a game with Ireland and saved it at summer 1700 and then quit the game and installed Trasibulos' mod and his version of startpos.esf. So that way I am playing as Ireland but with every component of Trasibulos' mod installed.
Perhaps the reason that it's not working is that it needs to be a savefile created with Trasibulos' startpos.esf file?