No strongholds will generate in a superflat world, despite them being specified in the exported world JSON. /locate fails.

If both old-style (i.e. stronghold,  distance, count, spread) and new-style (i.e. minecraft:stronghold, spacing, separation, salt) stronghold structures are specified in the generation JSON then the /locate command and eyes of ender will point to locations in the world, but those locations will not contain strongholds.