@Arbnor45
Hello,
If you enjoy playing without transfers I would suggest you to try some leagues where transfers are disabled (Nostalgia, national teams, other historical league). I think there is more that dozen custom leagues available where transfers are disabled by the game.
There is also option to open your private league anywhere (Premier League, La Liga etc.) and when you are opening the league you have the option to disable transfers, boss coins usage etc.
As for the buffs, aside from nationality one you also have buff for having all players on their right positions and also there is a "side attack buff" - if your right side is filled with high quality players and opponents left one is weaker your right side can make a difference.
Anyway, welcome back to the game and I hope you will find a way to enjoy it even more.