Now that I think of it a bit more, perhaps we shouldn't rush with deleting labels.
Moldovan in the Cyrillic alphabet is not used much now, and "mo" is a retired language code, but while Moldova was in the Soviet Union, this language was the language of education, press, literature, TV, and other media for over a million people. So, it's valuable to have structured documentation about how are names of cities and villages in Moldova, names of Moldovan people, and a lot of other relevant things are written in this language.
I'm not sure that a label under the retired "mo" code is the right way to do it. Perhaps we could have labels in ro-cyrillic, and perhaps we could have this data as Wikidata property values rather than labels. I'm not that much of an expert in Wikidata to make this decision. But simply deleting labels without at least a bit of extra thought is probably not the right thing to do.