That's tuning llama which is allowed from what I understand. Otherwise why release it at all, it's not very functional in its initial state anyway. What that applies to is using llama outputs to train a completely new base model which makes no practical sense.

As for generating jsons, that's more of a inference runtime thing, since you need to pick the top tokens that result a valid json instead of just hoping it returns something that can be parsed. On top of extensive tuning of course.