Why do you class it as a formal Instagram account? They post what they want on it. It doesn’t have to relate to royal visits hence when they post birthday posts and Father’s Day posts etc.But this TS concert was not for the benefit of any trust or patronages.
So they were at the concert privately, and I just think it is strange that they post a photo from a private event on their formal "Wales" insta account.
It seems random.
Of course they can be friends with whoever they want, this is beside the point.
But they usually keep their private life private and do not publicly post photos from their private family life.
(Even if photos from private events ended up in the press)