I am just giving an update in case that it can help somebody..
After Coach not offering me any guarantee they could fix it, I had to ship it to them first, and the wallet I thought might work to swap the snap was sold already, I actually found very easily on Ebay the same magnetic snaps (worse quality and top not exactly the same), but I only had to replace the top, the bottom still matches perfectly with the new pieces. $6.00 for 10 sets.
I know that if one day I sell it, I will have to disclose the "fix" of course.
Much better! In the pictures of the pieces you see the old part with a screw and the new, one whole piece.
I think it looks perfect! Happy you were able to find a replacement! I agree, it'd be good to note if you ever sell to give buyers more info on your bag's history & authenticity.