Hey Mikukasa1, sounds like you're back on your main account and getting no errors anymore. Great! 👍️
Yes, Microsoft accounts can be set up with third-party email providers like Gmail. That's fine and normal. It won't cause any problems with Wurst.
LilSkittle Reinstalling Wurst is unlikely to make any difference in the case of problems with AltManager, as the .jar file itself is stateless. In cases where AltManager won't open because of corrupted files, deleting the files where Wurst's alt list and encryption keys are stored could help. But that would also delete all alts, so a lot of caution and backups are needed when doing something like that. I wouldn't recommend it in this case, because there are no signs of a corrupted alt list here.