(I’m going to assume you’re talking about Expert Server and IFATC…)
IFATC is very-well trained, so they generally won’t make any errors.
But in the rare cases that they do, PMing them is the best option (like you said).
This doesn’t seem to have any problems; I’ve never seen an IFATC controller do anything wrong before, so I don’t think a specific Expert Server ATC reporting feature is necessary. I’ve contacted IFATC officers in the past, and they’ve always responded to my questions/comments within the hour.
But if you’re talking about Training Server, that’s just how things are. TS will probably always be a mess; it’s where people are supposed to learn what not to do before they get to IFATC’s level. In other words, reporting ATC in Training Server isn’t necessary because there isn’t anything required of ATC in TS.