Given their close proximity to each other, have the Redwynes and Hightowers ever gotten in each others hair? Two regional powers so close to each other can’t always have been peaceful.

It would not surprise me, although I imagine there probably was some element of stalemate, with the Redwynes unable to breach the walls of Oldtown and the Hightowers unable to muster enough of a naval force to safely land their land forces on the Arbor.