Thread:Support/Plural support

I noticed that some translators used PLURAL in some of the following messages although it's not in the original English one. Is that ok?
 * MediaWiki:Mobile-frontend-time-precision-Mannum/en
 * MediaWiki:Mobile-frontend-time-precision-BCE-Mannum/en
 * MediaWiki:Mobile-frontend-time-precision-century/en
 * MediaWiki:Mobile-frontend-time-precision-BCE-century/en