We're trying something new to allow for better localization of plural forms. The new string fileInterface.itemsWereImported has the following English value:

%1$S item was imported;%1$S items were imported

These are two separate strings, corresponding to English's two plural forms ("1" and "everything else"), separated by a semicolon (without spaces around it). Zotero code will automatically choose the first or second depending on the number being inserted.

When localizing this string, you should include as many plural forms as your language has, in the order described in this documentation from Mozilla:

https://developer.mozilla.org.cach3.com/en/Localization_and_Plurals

So Chinese would have 1 form, French would also have 2, Russian would have 3, etc. The plural forms will need to be in the same order described there to be chosen properly.

Also be sure to keep the placeholder strings ("%1$S") intact so that they're replaced properly.

If this works, we'll go back and fix additional strings that are currently based around English plural forms so that you can localize those properly.

Let us know if you have any questions.

Thanks!