Plugin generally works, no errors displayed. No stray file left without collections (I had three with the othe python script that were always left out). No obvious problems with cyrillic names. I only tried creating collections by authors - I commented out other two options.
1. Collections are sorted in apparently random order, no relation to alphabetical order, English and Russian authors mixed together. I can't see any logical order, looks completely random. It should be sorted alphabetically initially (then I think Kindle would put collections you accessed recently on top).
2. For authors that only have one book in my Kindle, collections were still created. Those single books should be left alone, or like the other script there should be an option how many books is enough to create a collection.