According to Andika Triwidada’s notes, it’s time for all Indonesian translation team to return to right way. On this documentation, it stated that Indonesian plural form is using the form below.
Plural-Forms: nplurals=1; plural=0;GNOME also use this form for Indonesian, but on LIbreOffice Pootle, those plural form never show when we used Indonesian UI on LibreOffice.
On gettext manual, it stated that the right plural form for Indonesian (Austronesian family) is Two forms, singular used for one only.
Plural-Forms: nplurals=2; plural=n != 1;
So, 2019 is the time to move to the form stated by gettext. I made this repo for GNOME Indonesian translation team for listing the .po files that using the plural form.