Honestly, going after the FBI for lying to the Finnish police would probably be a pretty hard case to win. Especially considering how blatantly unreasonable the behaviour of the .fi authorities has been.
It's possible that I could win. But that wouldn't really achieve anything, it wouldn't make the .fi authorities stop.
The best option I have available is to keep fighting my charges in Finland, as no matter whether I win or lose it'll be significantly harder for any other country to prosecute me for those same crimes. The courts here are fairly reasonable, while they require ridiculously low standards of proof, you essentially have to kill someone to actually go to prison here. Perhaps that makes it easier to say "guilty" just to play safe, keep the LE and prosecutors happy.