I know that i am a bit late, but i will try to answer your questions.
Cyan's ModKit is intended to be compatible with Forge, Fabric and Paper.
Cyan's ModKit uses the official class namings, so it is quite different from Fabric and Forge.
Cyan's events run asynchronously
The Modding Toolkit is still pretty unfinished, more features will be added in the future
Cyan is not complete, but it can already load mods and coremods.
There are a few mods available, the mods i have created are on my new GitHub profile
About CyanFabric, CyanPaper and CyanForge: it is slower when running Cyan, this is caused by FLUID's mappings processor used to remap transformers before applying them, this is not really a problem when you are ingame.
Cyan is currently not compatible with Quilt, but i might add support for it in the future
I do not have a public Discord server and i don't think i am going to create one yet, maybe in the future