Breakers with adjustable thermal trips are not allowed to be used here in the US in the same way as they are in other parts of the world, that's why you don't see them listed as an option for the SCPD in the NEC 430.52. So most likely, you have an MCC built by a foreign (to us) supplier, in which case the values they pick will not have validity here anyway. So trying to reconcile their settings against the NEC is futile, it was not supposed to be there in the first place. Adjustable thermal-mag breakers cannot be UL489 listed for providing branch circuit protection, they can only be listed as "manual motor starters", thereby requiring ANOTHER OCPD device such as fuses or another UL489 listed breaker ahead of them. That makes them difficult to implement on individual starters, such as in an MCC.
One problem with adjustable trips in a circuit breaker being used as the motor overload protection is that when there is an overload and it trips, there is a tendency here to tweak the dial up, usually under management pressure to get machinery running again immediately, no excuses. Yes, it's short sighted, but unfortunately very common. I would venture to guess that is how yours ended up at 185A, too high for a 100HP motor. It's possible that when the foreign MCC first arrived and a US electrician went to hook it up and set up the trips, he used the sizing rules on T-M breakers in the NEC, which do NOT apply to those adjustable trip breakers. Or they were set up correctly initially, then something tripped and a maintenance guy tweaked it to make the problem go away, justifying the setting using the wrong rules, then went back and tweaked them all using the same justification. Might be worth checking everything else in that MCC just in case.