On my Bally “Monte Carlo”, the lock RE. really does nothing more that turn on the GI lights and release the Game over RE. But can be de-energized when the delay RE is energized. Which was not straight forward on the schematic.
On your Schematic, looks like both the game over trip coil and the Lock RE. energize, this will de-latch the Game Over RE. then the Lock RE will de-energize the Game over Trip coil, Needs to be de-energized, because latching of the Game Over RE is mechanical. (Looks the same on my Bally)

It’s a start.

I’m sure this is true.

Thinking more about it, it’s all just a case of timing. If the gap on the switch of the lock relay is wrong then you could have a problem. If you tried to use the G.O. RE. to control the release coil, the switch timing would be critical, maybe why it is the way it is. Bally and Williams both use this method on many machines, must be the best and/or cheapest solution.

Steve, during another post I realised the purpose of the lock relay on your machine (And others). It insures that the machine is at a known position at power on, “Game Over”. If you turn the power off in the middle of a game then back on, you will be at game over.