I seem to remember the SGB2 having its own oscillator at 20 MiHz (20.97 MHz), which is what lets it run at a Game Link-compatible speed in the first place. If you defeat the CIC with a lock-on, I'm guessing that an SGB2 will run at correct speed, dropping frames like the original PAL Super Game Boy does.
TCRF's article mentions a region lock that was present in the first revision of SGB1 but dummied out thereafter.