How would the ponies react with them around.

5574025
Well, I mean, what's there to really react to, as far as what they are?

I don't think the reaction would be that much different, compared to if a normal shinobi showed up. They DO have horns, and they're eyes wouldn't exactly be inconspicuous, so they'd garner some attention. Considering they've never been seen before, and they're not minotaurs (Which I'd assume the ponies would think of them as, in the beginning at least.).

Hagoromo would possibly want to learn more about the magic in the air, and about how all the ponies are connected via friendship, and their CMs.

To this day I still don't know much about Hamura, though that might just be because I didn't watch the fillers about him.

5574025
Probably freak out a bit.

I have been saying this alot but i would see them as Kirin.