TrickFlow 190 Issue

Taking .012" off the OD of a 1/2" bolt would reduce strength by 5%.
To gain back any lost load would mean to match the strain, which would require a 5% increase in torque, so long as there's at least 10% margin left in the design of the stud, it should be fine.

I'd rather have an iffy head stud vs a head that tf will no longer warranty and which may develop a hole. If an issue ever develops with the stud, it's not hard to remedy or take a different approach.

The grain structure of a through hardened fastener isn't going to be affected by such a small reduction in OD. It's not case hardened, and isn't strain hardened like 300 series stainless..