UI problem (translation)

I want to create an interface, write the names in my language (Russian) into the Text element, but when I try to specify the text in the editor field, I get an empty string.
When you try to specify the name of a field in your own language through the nodes, the error “character 1: Malformed file. Source files must be encoded with UTF-8. "
Is this an engine bug or is it necessary to add an appropriate font in Blender preferences?
The editor interface, as I understand it, should be recompiled with the required font anyway.