Foreign (Bengali) unicode characters cause rendering issues

[Andriamanitra]

Description of the problem or steps to reproduce

Open a file with some Bengali text in it and move around a bit with the cursor. Some characters are left behind and even some line numbers disappear temporarily.

You can use this bit from Fedora's chromium-browser.desktop to reproduce the issue:

[Desktop Entry]
Version=1.0
Name=Chromium Web Browser
# ...
Comment[bn]=ইন্টারনেটটি অ্যাক্সেস করুন
# ...

(depending on your browser/fonts it may not render correctly on Github but you should be able to paste it into micro)

Here's a short demonstration of what happens using Asciinema:

I have confirmed this is a micro specific bug rather than something to do with my terminal (or other setup) – I am able to view the same file without issues in the same terminal with other programs (nvim, kakoune, helix).

Specifications

Commit hash: 1231d24 (version 2.0.13-dev.8)
OS: OpenSUSE Tumbleweed
Terminal: happens in all terminals I tried (xterm, terminator, gnome-terminal)