It's the same for when you reincarnate, just because you are in a new body doesn't mean you can get drunk because you are old enough even tho your body right now is of a 2 years old kid or just because you were 50 years old, you will now in your 6 years old body will look for someone your mental age and date a 50 years old person in your current body of a 6 years old kid?, regression and reincarnation both are a restarting point in where normally you wouldn't remember, but the only difference is that you have memories from your previous "life" So I think that any kind of romance is acceptable in regression and reincarnation stories.
As long as is not an adult dude (like, the body and mind of an adult) wanting to date a minor, then I think it's fine.
You know I have to do this: