I have never heard any dialogue between the new and the old hunters, do they hate each other?
Nope, they just haven’t been recorded yet!
They do talk to each other. Crow isn’t much of a talker though.
Well not a new conversation, there is a dropship conversation possible in which they can participate
There are cross talk btw when hank asks if shield full of juice torv replies Yes
That’s just a mix and match dialect.
Hank deliberately only call them by their class so anyone can respond with a simple ‘yes’.
I’d imagine it’s neither cheap nor easy to get every voice actor to return with every new Hunter and Monster released, even worse if they add in a new game mode
Its also quite possible that TRS had a damn good idea during their years of developing this game for other hunters that were not practical to do/finish within the time/budget restraints for the core game, and had the original voice actors record extra lines in anticipation of them getting to complete the characters they dreamed up/wanted to do/couldnt originally.