I think “triaged” is not quite the same as “acknowledged”. For example: someone reports a bug in some stdlib module. A triager reproduces the bug and pings the relevant expert. Arguably the issue is now triaged, but the triager is not an expert on this lib and cannot say whether this is a bug or user’s misunderstanding of how the library should work on some edge case. So the bug report is not acknowledged yet.
I actually don’t think “triaged” is a boolean state, it’s an ongoing process.
I don’t know whether it’s better to add an “acknowledged” label or an “unacknowledged” label that gets added to all new issues and is later removed. I don’t know if it matters much which way (in both cases we have the question of how we acknowledge the current open issues).
We currently have an “invalid” label (I think we quickly close those issues, not sure why we need the label). How about we add a new “valid” label and then an issue can be “valid” or “invalid” or unlabelled. A core dev’s adding “valid” could be interpreted as “I think this should be done and I am likely to help review patches for this”.