So how do they internally aggregate an image of your fingerprint during actual usage, then? Also, hash plus salt together is info that identifies a fingerprint

So how do they internally aggregate an image of your fingerprint during actual usage, then? Also, hash plus salt together is info that identifies a fingerprint. Why shouldn't it be possible to leak that info? Once you have it, you can apply it to your existing database of fingerprints to get matches - no actual fingerprint image needed...