Negi95

What Naruto met inside the "Jinchūriki space" was a remnant of their chakra, not them, he can't possibly remember that.

"repulsion wave"... if it had color it would be more of a wall against a beam than a classic "beam struggle"

Where does all that chakra comes from? He clearly didn't get nearly enough from the first 5 tailed beasts to use so much

A'fei?

I don't see how them being in Ars would stop the Sword God. Maybe being inside the palace, but I have my doubts about that too.

I wouldn't say he should do it as many times as he can, but he does need the boon all things considered

I'm still at chapter 72 so I don't know what happens later on. You are right that learning those things is useful in general, I just think they a pretty low priority in their situation.

You make a good poin, I only wish the author himself would give that kind of information rather than make readers randomly guess about it

You know, I really didn't remember that, I was sure it was a raven, lol

I mean, dumbledore being willing to do anything for the prophecy is what led to his death 6 times. I wouldn't count on the old man not doing something stupid for one of his plans and losing my last chance, I think that's a bit too big of a gamble.