So then an adaptation of the appendices from one of those books is covered. They were piecemeal from the whole legendarium. As in two of four things published by him prior to his death. If the second age was intended to be part of the same story then that implies he is okay with second age stuff being adapted even if he didn't publish second age stuff prior to his death. As he sold the rights to some of his story yet intended it to be a whole. You again prove that you are wrong lmao.
Of course the story of this show isn't canon. I'm not sure why you are now bringing that invention of yours back into this discussion. The question of discussion is adaptations and if Tolkien wanted adaptations.