What I mean is pretty much to classify the issue by adding all the applicable labels and possibly @mentioning relevant people, or close the issue if it’s clearly invalid. Maybe unclassified is better?
This can generally be done rather quickly, even without fully understand the problem. After the issue has been classified, the untriaged label can be removed and an “expert” can pick it up from there. You may also decide to spend some more time investigating the issue yourself, looking at the code, trying to come up with solutions, and possibly even proposing a PR and fixing it.
The goal of this label is just to provide a convenient way for triagers to know which issues they should look at without having to actively chase new issues, in order to make sure that every issue gets at least seen and classified. In general we would only have a few recent issues with the untriaged label. This is assuming we need a label to ensure that issues don’t go unnoticed in the first place.
This was pretty much the role of stage field on bpo, but it was decided to remove it.