Plural source strings are supported for translation, but there are two cases where it can be difficult to translate still:

1. When it is known by developers that the number will never be 0, the translation can be needlessly complicated in languages that use {0,1}for singular.
2. When it is known by the developer that the number will be neither 0 or 1, the plural form is copied to the singular form at purpose but it makes little sense in translation.

See for example tag's entity list (in tag's overview tab).

Even though code comments are sometimes provided (as in the above example), this information should be made directly available to translators instead.

An improvement could be to set the range flag in POT files for those plural source strings.

References:

• https://www.gnu.org/software/gettext/manual/html_node/PO-Files.html#index-range_003a-flag
• https://www.gnu.org/software/gettext/manual/html_node/Plural-forms.html