Yes, MP appears to know nothing about BLH telemetry.
Yes, DF logs are the place to look for evidence of working BLH telemetry.
Yes, new OSD code for F4-based ChibiOS-based flight controllers have option of showing BLH telemetery amps, temps, RPMs.
CRC error was fixed several months ago by BLH team. IMHO, if you are still seeing that, it’s not because you have a certain debug flag on, but because you’re running a version of BLH firmware that pre-dates the fix.