There have been examples where people have reapplied name:ru values from 10 years ago (see e.g. discussion here), and where reverts of mass name:ru removals have in error restored old name:ru values for streets that have been renamed. I have an open DWG ticket for this, and am gradually going through a historical “old_name:ru” query to fix these, but people locally in the relevant town are best placed to know what is the current name:ru (if any). In cases where streets have been renamed, it probably makes sense to have the old Russian name in old_name:ru so that it’s obvious to people in the future that if name:ru matches old_name:ru, it’s likely to be wrong.