I doubt it.
when you exit a tor node onto a website, logging in exposes your real ip address briefly
Dude, that's a major problem. Have you notified the Tor Project developers about it? And the CIA? And the NSA? And the FBI? I'm sure all of them wish to have that exploit also or maybe even fix that shit!
Are you a fan of "full-disclosure"? You should! That's how you do security!
BTW, how do you have access to the IP's people use when logging in, Pi Coin? Are you one of the forum admins? Because if you aren't than something strange is going on... Or did I misunderstand your statement?
You need to be more specific and explain every little detail about who you are and what you're doing. Or we can just assume things about you. Without further details from you, I'm assuming you are an hacker and that you hacked the forum.