How do I keep my enchiladas from getting soggy when they cook?
Two things:
(1) Pass the tortillas through hot oil first, for just a few seconds. That will soften them and also "waterproof" them. It is the traditional technique.
(2) Consider making them on a griddle instead of in the oven; preheat the sauce and the filling, soften the tortilla, fill, heat for just a few more seconds, place on top of the sauce on a preheated plate.