After pasting the text was all '?' inspite of proper Russian characters. I had to convert the file with distorted text with all '?' to UTF-8 BOM, then to copy text once more in browser, then paste once more into Notepad++ to get proper characters pasted. The procedure was necessary after any later changes in file. It was even more problematic with UTF-8, I was able to get proper Russian characters pasted as with UTF-8 BOM, however the characters were always distorted again after program restart. I fought several months with the issue and could not understand what was the logic, it looked like a hardcoded codepage would be used istead of UTF-8 if created the new empty file (UTF-8 BOM set in config for new docs), pasted Russian text, saved, restarted the program. Everytime I changed something later and simply saved but omitted to do 'Convert to UTF-8 BOM' + Save, the whole text was distorted again.
Similar problems occured even with some other languages with more exotic latin code page (for Central European Windows-1250 the character 'č' was lost after program restart if file had *.nfo extension f.e.). Hebrew worked not at all, I solved that via conversion into HTML character entities. Notepad 7.9.1 x64 on Win7 SP3 x64.