https://wiki.openstreetmap.org/wiki/Any_tags_you_like suggests that it's okay to start inventing new tags if there's no good existing tag, indeed this is how new tags come about. People start using them and eventually as the usage is refined they get documented as in-use, or they go through a proposal and get documented as approved.

I can't see any glaring issues with `privacy=limited` in this case.

In any case https://wiki.openstreetmap.org/wiki/Key:note is used to inform other mappers but in this case https://wiki.openstreetmap.org/wiki/Key:description would be better as that's for informing map users.

I'll update this to restore the privacy tag but also convert the note to a description.