If one is desperate for a "fails/mistakes" kind of verb then "BREAKS" (as in "includes breaking changes") might actually hold sway, but then you'd leave out the "major functionality added" scenario for, well, MAJOR.

In short, I think OP's observation is that of a pessimist's.

If not "MAJOR.MINOR.BUG" (which needs no improvement IMO) I'd go with...

TECTONIC.FEATURE.FIX.