I know the mods of a community are able to see the user who reported a.post/user. Pretty sure info is available to admins. However, I have not seen evidence of that info accessible to the general public.
I've reported a user and got an admin response right away. I know they see the messages. They are likely leaving them as reports just to give the mods something to do given the actual size of communities and Lemmy overall. If someone is trolling across multiple communities, just add ATT ADMIN and they'll take care of it I'm sure.