[glang]

I think were talking the same but theres something here I dont agree with:
Those thyristors act as crude crowbars to short circuit across the generator, causing voltage drop because of the internal resistance of the alternator. They're on/off devices and connected parallel to the load, so they operate independently of load current
Thyristors/transistors are not on/off devices but variable chokes that are controlled by the regulator depending on system voltage. As you then say the current they let through isnt absorbed by the R/R but generates heat as it passes through the transistors which must be dissipated to avoid damaging them.