A loose compensator bolt will give you a bad knocking noise like a bad rod sound, the burnt smell you have is usually a sign of a burnt stator. IF it was the compensator bolt loose, there is no following damage in itself from that, just has to be re torqued after the "fix" suggested here.
Doing the compensator bolt is an easy fix but you should ask them to install the washer that allows the proper torque load to be applied on the stack up on the compensator so it doesn't happen again while they have it apart (probably replacing the stator).
Compensator Nut Re Torque - Harley Davidson Community