User:小老虎3018 reported at https://www.mediawiki.org/wiki/Topic:Ut0zvcbdcwhsdfmd that non-Latin characters caused improper selection in the visual mode: "When I selected some characters in line X, and 'Delete'. Words in line X+1/X-1 has been deleted."
It was difficult (impossible?) to insert characters at the head of the line.
Bug appeared while using Chrome 71+, Windows 10 (1809) and MS Pinyin IME (Windows original). Cannot be reproduced on Linux.