Timofey,
There were one problem regarding collations, when you create Postgre database with es-ec or es-ar encoding, not just ES, it failed. For now we are creating databases ES only, without specifying the country. And it work for us.
Another problem is about searching. If I write "búsqueda" to the database and will try to search for "busqueda" there will be no results. I think it is a good idea to use CI AI collations by default. There are a lot of languages with accents or extra symbols.
I do not remember the linux problem. The last time I was using it, it was painfully slow in designer mode so I switch back to windows. It was beta 8.3.1. I will definitely check again linux version, probably 8.3.4.