So one solution I've used in the past to get WFC unstuck from local maxima is to keep a counter for each tile location with how many times it has gotten stuck at that location. Whenever it gets stuck it'll reset all the tiles within a radius relative to that counter. First time it gets stuck it'll reset all direct neighbors. Second time it'll reset all direct neighbors and their neighbors etc. For the tilesets I was using it'd hardly ever have to reset the same spot more than twice, which kept things relatively fast. It has the nice property of eventually guaranteeing a solution, though that may involve resetting the entire map many many times if it's a sufficiently gnarly problem.
This is a nice solution. I came up with something similar where once it got stuck without making much progress I would just blow away a big radius and that would often help it get unstuck. I did eventually abandon this approach though. I can't remember the exact reason why but I think my back tracking system was not compatible with it. So if it got stuck after blowing away some tiles then it would be truly stuck and could not backtrack anymore.
Mine didn't even have any backtracking at all. It'd just keep blowing stuff up until it happened to stumble on a solution. Obviously that only works if your tileset allows for many solutions, if there's only a single solution to an area it'll take a long while to stumble on it.
