Hi there!
Is the List Window "hide unread books" enabled? If so, books will only be displayed after you mark them as read with plugin commands.
In theory, using the cyrillic (or any other type of alphabet) should not be a problem. I have never tested it though, so I would not rule out this possibility completely. The plugin has no restriction to using book titles or categories containing multiple words. The only thing is that when using the plugin manager as source the plugin automatically trim out blank spaces to convert the title in the book key to be referenced in plugin commands. For example, if you name your book "Это тест" (used google translate here hehe), when using a plugin command to read it you would call it "Этотест" (that applies on both MV and MZ). The title displayed on the menu is the one with blank spaces, you just need to remove them for the plugin to locate it.
Let me know if this solves your issues. If not, I may need your help setting up a test project replicating them so I can take a look. I checked on my sample project and was unable to find anything (using western alphabet though).