As a break from the previous theme, "splash" and "mountain" are right out. Especially 'mountain.' It didn't make sense to call it 'mountain' the first time around.
"Falls" is problematic if the new ride has no falls. For all we know, the story of the chute could be a giant wave and not because of falling down anything. If the descent is a one-time thing in the story of the ride... then there are no falls.
Tiana = The protagonist is upfront and center, which is the intention of choosing her. Using "Princess and the Frog" in the title would be way too much considering people think TBA is already too much.
Bayou = In place of "splash" indicating it's a wet ride, we have "bayou" indicating it's a wet ride. This is also place-setting (albeit, more important for DL than MK).
Adventure = It's a ride. A thrilling one because of the drop. It's not Tiana's slow boat ride. It's not Tiana's restaurant or a Tiana M&G.
The concern over the title is full of high drama despite being relatively unimportant. Is this what we can be looking forward to for the next two years. That all those who didn't want a retheme will be picking apart minutiae? To what end? Convince WDW to scrap the retheme? That ain't gonna happen.