This is true that the sync lights do not flash.

If you were in the real plane and connected the generator using the middle switch called the MGR (main generator relay) you would have auto protection to sync with the sync bus. The system would only close the MGR when the lights were out. Now, if you were to connect to the sync bus manually via the BTR (bus tie relay) you would have to use the generator frequency knob to change the speed of the CSD (constant speed drive) to get the flash rate slow enough to close the BTR when the sync lights are out.

This is much easier to demonstrate than to write about.
If CS fixes this problem then you can have fun shearing the generator drive shaft!  ;D

Lou