How to localize yii2 using po files?

Question

Yii

I want to localize a project on Yii2, using .po-files for storing messages for further editing them in PoEdit. Faced the following difficulties:

1. How to generate a .po file with plurals? Yii only generates msgstr, but I need msgstr[1], msgstr[2], etc.
   
2. What about sentences with multiple plurals? For example: "2 cats and 1 dog participated in the race." The PoEdit interface assumes that only 1 plural number will be used in the sentence
   

Or skip PoEdit and use the ICU sentence format like 'This is {n, plural, one{item} other{items}}.'? But how then to explain to third-party translators how to work with this format?