The title may sound generic, but it's indeed a problem that happens on a lot of sites and pages, essentially making CX broken in production.
To reproduce, Try to translate the article Кашира from ru to ba.
Click on some paragraphs and try to type - and it will be impossible, and there will be a JS error about templateData.
This happens when I try to transl articles from the Russian Wikipedia. Maybe it happens with other languages, too.