I'm assuming that the author of the first message of a chat room transcript was the one who established a chat room.
If I'm wrong, how else can I find out who first established a chat room such as
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You can follow these steps to find who created the room: (using The Tavern in my examples)
Go to the "access" tab of the room:
View the list of Owners:
Go to the "general" tab, and search for messages containing "owners":
Filter the results to get only messages by Feeds system account:
Go over the results, and compare with the list of owners from step #2. The one user who was not added by anyone else, as can be seen in the search results, is the creator of the room. Looks like Tyler Carter created the Tavern.