That may be a translation confusion?
I don't suggest that in the least.
OTOH i actually know that some used levels get warped & some have huge dent burrs from poor handling, probably not from the users, but from the acquisition and vendor chain. If you are buying *used* precision levels it might or might not be worth verifying the bases start in the condition you prefer, for your preferred work.
Once the frame condition is known, proceed with routine calibration of the vial, a relatively simple task.
I think i get that it does not matter to you.
It's almost comical that it seems to make you irritable.
smt