Well, sorry to tell you, but currently there are no logs for discussions. Only temporary logs in the recent changes tab. Naturally, you should report this incident to fandom staff fandom.zendesk.com/hc/en-us/requests/new
I mean, they might have implemented a new backup system, between now and when I asked them last. But I wouldn't bet on it. So contact them. Otherwise just continue posting on your wiki, surely you can move forward.