Hm, at least on their homepage, they don't mention the ability to do group video calls or screen sharing, do you know if it's a complete replacement for Discord's feature set? The reason I recommend Movim specifically is that the only features its missing compared to discord are the rooms, and it cannot yet share application audio when screen sharing (but should come later).
Movim is also built on the battle proven XMPP framework, which also allows for easy self hosting and access to the wider existing XMPP community.