Having had the same argument at work in the past, I feel your pain. Trying to migrate away from massive SQL files and random strings here and there to a collection of interdependent composable SQL builders is apparently a tough sell.
Obviously that is just one persons experience. But I'd take a single crazy sql file any day of the year because it's insanity is scoped to that file (hopefully).
But I'd agree the random string are no good. Maybe refactoring them into an enum either in the code or in the DB would be a good step forward.