Hello my friend!
I got messages.yml file translated to russian, moreover, I mad my own. But every time I try to use it - plugin don't work. Spigot 1.8.8
(tried almost any verison of ur plugin)
log part:

latest.txt

Hello!
If you can upload the messages.yml file, I can take a look. A couple of things to note:

1. You generally don't want to edit the keys, the parts of the YAML to the left of the : It looks like from your error message that you have done that, though I'm not sure.
2. You may need to put double-quotes around anything with special characters- I'm not sure about that, but definitely if you've broken rule #1 the key will have to have quotes.

I don't generally do private work and haven't really had time lately in any case- but I can definitely help get the translations working, it's hopefully just a matter of quoting things.

The 1.9 ones should work on 1.8, though some of the keys and instructions may have changed- you can stick with the 1.8 one if that one's more working. Anyway, if you can link to whichever file you'd like to get working, I can take a look when I have some time!

Sorry, for the localizations I was waiting for you to link to the files. I can't really tell what's wrong unless I can see them- can you put what you're currently working with up on hastebin or something, please?

For your visualization question, you need to use the Magic resource pack (or make your own) for the spell icons to show up properly.

This is the RP you want for 5.x :

https://s3-us-west-2.amazonaws.com/elmakers/Magic/Magic-RP-5.zip

You need an older version of the RP, try the one I linked to. Spell icons in Magic 5.x are skulls, in 6.x they are items.

For the skulls, you need a special file in the RP to make them look flat, this is not in the latest Magic RPs.

Icons for 4.x are skulls, too. They had been skulls for a while, until MC 1.9 allowed me to use retextured RP items instead.

You'll need the older RP if you want them to look flat in Magic 5.x

Ok, I finally got to try this out myself and I think the problem is what I said earlier- you have to put any special characters inside of double quotes. For example, your original "general" section won't load, but this will:

general:
    no_spells: "Вы не знаете никаких заклинаний."
    no_spells_in_category: "Вы не знаете заклинания, которые относятся к категории: $category"
    spell_list_page: "Вы знаете $count заклинаний.[Страница $page из $pages]"
    spell_list: "Вы знаете $count заклинаний"
    locked_chest: "Этот сундук закрыт, вы не можете его разбить."

If you put everything inside of double-quotes like that, it should work.