Hello Μikhail,
Thank you for reaching out to Transifex.
I am Antonis, a support engineer from the Transifex support team.
Thank you for bringing this issue to our attention. Typically, you cannot save partially translated pluralized strings. As you can see, our editor doesn’t consider them translated strings. For the strings to show up as untranslated, you will need to edit them and provide translations for all plural forms.
Keep in mind that Transifex follows ISO Standards and Unicode CLDR data for our supported languages. When they get updated, we let you know in advance if they affect any of the languages you’re using. You can find information about the latest changes here.
Please let me know if you encounter any issues with this process or if you have any feedback, and I will be happy to assist you.
Kind regards,
Antonis