I’ve never heard of a user stripping the threads. I’ve not heard of threads galling, for that matter, and stripped threads are usually the result of galling being allowed to continue without attention. The material is an aircraft grade aluminum and tough as hell. We have had a few on the forum here who have bent the jaws by over-tightening, but stripped threads is a new one. Of course, I’m not a member of WE’s service department, so it’s possible that it does happen here and there.
I’m only slightly familiar with Helicoils, but I think they’d work pretty well and there’s lots available for the 1/4″-28 size. That said, you have a lifetime warranty on the system, excepting wear items. Sent an e-mail or call their customer service guy and I’m sure they’ll ship you a replacement right away.