I think training this as a separate head on top of a frozen AlphaZero model makes a lot of sense. I don't think anyone has figured out to do language learning with reinforcement training.

Actually, I can't figure out from your explanation why you trained the whole network yourself instead of just using Leela's network and training the commentary head on top?

If you wanted to in-cooperate the search, maybe you could just take the 1800 or so probabilities output by the MCTS and add some layers on top of that before concatenating with the other data fed into the transformer.

In either case, this is a fantastic project and perhaps an even more impressive write up! Congrats and thank you!