The funny bit is I can absolutely see how the entire cycle went, as I believe they had Internal Slack for stuff along with basically everyone using Twitter/X. Discord's penetration in 2020/2021 wouldn't have hit Japan in the slightest, being still primarily PC focused still at that time. But collabs by the time of Council were heavily Discord based, but Cover simply wasn't setup for Remote work in the same outside of Japan as they are with basically everyone having been in Tokyo. Also, between Twitter and Line, they didn't "need" Discord.
However, having an official Discord meant corporate accounts and all of the fun jazz of Japanese Corpo Autism. 2024 sounds about right on timelines.