I'm not the pack author and I don't really know much about the mod that's missing, but one work-around would be to make a custom install on the twitch client using the same version of forge. You can download the server pack from the files list which includes the mods, then copy paste the mod/config/libraries/scripts folders over to your new profile's folder. That should work for now, although you might be missing one or two client side mods (not sure). I haven't tried this myself, but that should in theory get you up and running until the pack author updates the pack to remove the missing mod, or the mod gets re-uploaded.
Update: Just tried this workaround and it looks like all the mods and client side configs are working as intended. So if you need to install the pack now while we're waiting on an update, this works well.