Does anyone think that Terra should be in the upcoming Teen Titans series? And if so, should she be a hero or villan?

No, I don't think she should be. Because in the final episode of Teen Titans, Terra said she was not going to join the Teen Titans and it would confuse the viewers even more.

Actually, I think she should. Because there was an episode where Beastboy found Terra. So I think they should try to make her remember who she is.

She should come back and a hero

Yes, villain