Keep in mind that the Forgecraft server is a testbed for mods in a very alpha state. As often as you see problems happen with Forgecraft,I flat guarantee you are only seeing a fraction of the crashes and other problems they're fixing. Which is really the whole point of the Forgecraft server... it's basically a closed testbed to fix things that break as they break and get additional pairs of eyes on it so they can figure out why it breaks.
As such... don't expect a stable and enjoyable modded experience on 1.16 any time soon.