A city has a Wikipedia page and a corresponding Wikidata-item-page. One of the item properties is Property:City_mayor.
If the mayor changes, and both have their own pages/items (http://de.wikipedia.org/wiki/Eberhard_Diepgen to http://de.wikipedia.org/wiki/Klaus_Wowereit for http://de.wikipedia.org/wiki/Berlin), changing the mayor would mean to disconnect/replace the item to item property. The change would be clean and logical with respect to translated labels.
However, where the city mayor is not a well known person (smaller cities), the City_mayor property is mostly likely a string literal.
Replacing the string (name) for the mayor in this case would require to empty ALL translations/transliterations in all other languages. Unfortunately, the system cannot really know whether an update of a translated label is the result of a correction (person did not change) or occurs as a result of changing the label.
The design of the UI should make this situation as transparent to editors as possible. It may help to provide two edit-buttons for language-sensitive string literals:
[edit translations] [edit new value] (or [replace value] ?)
In the second case, all existing translations would be blanked. Probably more or better ideas can be found... :-)
Gregor