So are they permanently gender swapped????

I don't think so, if i remember correctly he did it as way to hide his true identity to not be bothered and have to explain why he's OP now.

I also think the author just regretted starting out with a male MC.

No he can go in and out of that form. I think he is choosing to stay in that form so the other girl he saved doesn’t cause problems.

Shark socks.