I think it is a great idea!
I use it personally with my friend, and with a teacher from my college. It’s a quite good platform, in my opinion, of course. Because with discord you can chat with other and do some “mini-groups”. So it’s really useful for me when I do some groups work. Also, I use discord for the video call with my friends, and it’s a good option on the platform.
I think discord could be a good project because of the mini-groups, like that students with the same level or learning language can chat with each other. And because Discord is also an app, so there are notifications who are really useful, because on the forum I always arrive late for the new dialogue (I have to check my mail more often 
)
I hope my reply help you a little Max 