I have used Loc-It (blue) on all my scope base and ring screws for many years. It makes the threads "sticky" so vibration won't loosen them, but they are removable.
IMO it isn't really necessary to torque screws down REALLY tight. As long as all play is removed and they don't come loose, tight is tight.
As to your question about overtightening a synth, stock - even the strongest plastic can bend and/or warp under enough pressure.