Sublime text 3 search REGEX how to select all Russian words/letters in the text?

Question

Regular Expressions

There is a large file - for example, let's say snippets, consisting of Latin and Russian letters, so that the variables are written in Latin, at the beginning of the line, and the explanation is written in Russian letters. The explanation always ends at the end of the line. The beginning of the explanation is in no way separated from the text in Latin.
For example:

"fallback_encodings:" Использовать кодировку, когда она не может быть определена автоматически

When copy-pasting for JSON validity, the Russian explanation must be separated by // with a comment sign. Accordingly, the problem arises: How to convert the source file and insert a comment sign at the beginning of each Russian part of the line?
UPD: regarding comments in JSON - allowed in non-strict cases like mine :)
blog.getify.com/json-comments

Answer 1

The problem is that sublime3 regex understands [Az] but doesn't understand [A-Z]

I understand.
Possibly a coding glitch.

tyts