Thanks for your feedback. I have precision Ammo I loaded for an SPR AR15 a few years ago. It still shoots right on the money, even to the point of hitting a 3" gong almost dead center @ 400 yards. I had loaded up close to 600 rounds of it about 5 years ago or so for a 3-day SPR/designated rifleman class taught up in Yakima. This brass however was cleaned using a vibratory tumbler and walnut media.I understand your concern. I can't answer your question completely but here's what I've got.
My most accurate rifle will shoot 1/2 moa on a good day (a good day for me because it's stretching my abilities). I've loaded and shot ammo for it using wet tumbled brass but not a lot, and not stored terribly long. I can say I haven't noticed any problems at all at this point. I really don't expect to either, because the wax in question is actually a microscopically thin, hard, dry coating that I'm pretty confident is totally inert.
I don't blame you for being skeptical though. It would stink to load a bunch of rounds and years later find out they went bad. I had exactly that happen some years back when I used some old surplus H4895 that went bad. For a couple years I was finding odd batches of ammo that I had loaded with it. They were easy to ID because they had cracked necks with nasty green streaks coming out.
Sorry to hear about that happening to your precision ammo. That really sucks.