[blackadder]

The GARO Ankoku Makai Kishi Hen novel and Yoseki no Wana novel were written by Yuji Kobayashi, one of the main writers of season 1 and both were approved by Keita Amemuya. Seriously, how moronic can get you get? Fanfic because it's not happening on screen? Oh wow, I guess you really never heard of the many many Japanese media franchise that have novel and supplementary tie ins which are official? Just because the "main creator" doesn't write doesn't mean it's not official or canon, many of the idea still comes from the main creator but a lot of time they don't have the time write to all of them and because workload that would have been involved, they usually leave it to writer with their approval. Using novels and supplementary materials to fill in the hole in the main series happens a lot in Japanese media franchise and AFAIK, other media franchises as well.
So, basically unless you saw them on screen, you're not gonna considered it canon even if the main creator does? Oh okay, then why don't you just live inside your own little world called "Dr Kain's magnificent world where everything has to have my approval to be official"