help etiquette for helpers: flagging to request more help from others

[andresrcs]

I think you can simply say it, with something like
"Hopefully someone else would be able to help you" and if someone else is willing to help they will weigh in.
Also related to this, are the cases when the user constantly posts poorly constructed questions besides been asked to elaborate and provide a reprex, so we simply ignore their posts until they catch up with the good practice, otherwise we would be encouraging a bad behavior.

@dromano

which might be unwelcome?

Yes, this is definitely against the forum policies, see

FAQ: Should I @name mention other users in my post?

What is @name mentioning? @name mentioning is when you type someone's username with an @ preceding it. Doing this sends a notification to the user. Depending on their settings, it may also send them an email message. For example, with @JacqueHousteauGram in my text, Jacque here will be dynamically notified in community (and via email if he's configured for it). Please don't use this feature excessively In general, it is considered bad form to @name mention someone not otherwise engaged in the conversation. Why should I limit how much I @name mention others? It can be annoying Active people who were being frequently mentioned in topics were first to request that this practice be minimized…