The Huayan lineage in China seems to have been lost after the Tang Dynasty, though of course the history, texts and philosophy did not become unknown.
Huayan still exists in Japan as an independent lineage (called Kegon
in Japanese), albeit quite small. Their HQ is Todai-ji in Nara. I wrote up a description of the temple and the images:https://sites.google.com/site/dharmadep ... ji-in-nara
I hear much of their practices are drawn from Shingon, though of course they also have their traditional Kegon traditions.
The Hwaŏm school in Korea was merged into the Seon school, so it no longer exists there as an independent lineage, though the influences from Hwaŏm are strong.
Huayan as an independent lineage has been revived here in Taiwan in recent decades, though I'm uncertain about how successful they are. They have a temple in downtown Taipei which I visited. Very low-key.
The reason there is no forum for Huayan is because there are little to no formal practitioners of it in the English speaking world. There are works in English on Huayan and the respective patriarchs, though that's just academic writings and not something people practice. Outside of academia you'll be hard pressed to find anyone who knows much about the school, let alone able to read the original texts in Classical Chinese.
Huayan Buddhism as we understand now is entirely text-based. Zhiyan, Fazang, Chengguan and Zongmi are the key patriarchs, though you find other authors in Korea and Japan (like Gyonen) who wrote their own treatises. If you read Chinese or Japanese there is a lot of academic material on the school, though in English it isn't too extensive.