[vortizee]

For the benefit of others reading the thread, I always cut with separated bits. For example, I'll duplicate part of the object to cut, duplicate the cutting object, move them aside, make a backup of both and move those above then do the boolean.

If it works I reintegrate it with the original object. If it fails, I can try again with the duplicate backups. Duplication, separation and reintegration is one way of trying booleans without messing up your original object. Reintegration is easy using snap vertices by distance, if necessary, and optimize vertices/surfaces.