Just becuase the forums are not the correct place for reporting others doesn’t mean there isn’t a way to notify Bliz.
I’ve never used, or even looked for, any in-game reporting methods in D2R, so I don’t know if they exist or where they are. But if there are report options, that’s the appropriate place for reporting.
If there are no reporting methods in the game at all, the email hacks@blizzard.com can be used. Know that it’s a one-way report system; there will not be any reply.
As for what Bliz does about it, who can say. D2R is an older, essentially retired game. How much effort is put into policing it compared to the modern, active games isn’t really known. Could be the same amount, could be less.