Hello Anita Lund,
From your description, may I understand that you don't want the users to rename the teams and channels although they are the team owners? If not, please feel free to correct me. If I'm right, it is not feasible to do that. Given this situation, it is your submit your feedback and share your experience in our UserVoice service.
Regarding the problem about syncing, I did the same tests on my side. After I rename the team or channel, I'm still able to go to the SharePoint by clicking Open in SharePoint and the link wasn't broken.
To better help you, would you mind sharing any screenshots about the error messages or steps you have taken?
Thanks for your time.
Regards,
Seven