This has been done before, but never got a response. I'm bringing it up again (rather than simply reusing the last post which is effectively dead now) for a number of reasons, including that lack of response and the fact that there have been a few recent occasions where seeing this data would have made a significant difference in effective chat moderation.
Currently, there are two types of chat flag: offensive flags, and mod flags. On mod flags, moderators can see all the data about them: what message they were cast against, what the flag says, and who cast the flag. On offensive flags, we see only what 10k users see - which is only which message the flag was cast against.
It's a pretty well accepted fact that chat moderation is... not all it could be, shall we say. Well, this would make an improvement: there have been a number of cases that I've seen in my tenure of spam-spam-flagging (i.e. spamming spam/offensive flags). These events disrupt rooms by bringing in a Mjolnir of mods, and a plethora of 10k chat users from all over the network, all trying to get at the flags and (sometimes) have a dig at the room where they're cast.
Allowing mods to see who cast the flag would enable us to stop these cases in their tracks - we've got the tools to do it, but we don't know who to use them on.