I’m a fairly newbie myself, but my machining experience tells me the different direction of the texture patterns is to give some bite to keep the latch from moving horizontally and vertically.
Correct, there are corresponding ridges in the jamb and/or backside of striker itself to help anchor things when screws are tightened down. Forget if they're on both jamb and backside of striker, it's either one or the other or both. It's been awhile since I had them off and my memory is only good for about 10 minutes nowadays.
