Hey guys, so our team founder isn't active anymore. Is there a way to transfer team founder/admin to someone who is active?

Well, that's possible, but probably requires a lot of action.
First you need to go to every project which the team is active. Then search for the team there and request a founder change with the "Initiate transfer"-link.
However, this is time-dependent. Not sure anymore if it is 60 or 90 days, but if the founder doesn't answer it and declines the request within that time, the change will be executed.