After putting more thought into it, I think that I may have figured out the reasons why the scenes that I've mentioned before bother me.
A.) Because after such a long time of being made to assume that the current Alola cast didn't know very much about Ash's past successes and accomplishments, this seemed like the perfect opportunity to finally start letting them all just how experienced a trainer Ash really was by the time they met him. He doesn't know that much about the Alola REGIONbecause he's clearly still new that part of the world, but, for the first time in a long time, his class was on his home turf, a region that he's spent a great deal of time traveling in the past. But, then, just when it was starting look like his past accomplishments were just starting to be brought up to his Alolan friends, his original friends undercut the moment by pointing out one of his past follies in regards to his quest for Gym badges. This really underminded a pretty good opportunity for Ash's past successes to at last be brought up, instead of being made to become a part of the past no longer considered relevant. I mean really now, by this point, Ash should be carrying around quite the reputation as a very skilled and talented Pokémon trainer and having the fact that two of his first gym badges were not won in the traditional sense be mentioned and revealed really put him at risk of losing some respect from his Alola classmates and he really didn't seem to have all that much of that as it was anyways, especially from Kiawe.
B.) That one scene where Misty taunts Ash after their battle bothers me because it seems upsetting that after all this time she still hasn't gotten over the need to do that. You may call that sticking with her character, but I call it her never getting over a bad habit. Ever since at some point during the Orange Island saga, Ash had begun to taunt Misty less and less, up until his taunting of her, at last, ceased all together. Nowadays, all he ever seems to do is praise her and her skills as a trainer and a gym leader. So the fact that she still has the need to taunt him is very hard to fathom.