Change Admin Editor to Specific Font while editing Post of Certain Language


While editing the page text in the Admin’s editor, I need the text to show in another font when a specific language is activated. I can upload the WOFF or OTF or TTF into the server so the font itself is not a problem, but I was wondering how I can force the Admin editor to show the text in a different font while a specific language is selected.

For example, if the language is not Japanese, then the default font is perfectly fine, but when the post is Japanese, the editor’s font will be set to a certain font.

I was thinking of relying on the HTML lang attribute, but it looks like it is set on the account’s preferred language, and does not change based on the language of the post currently being edited.

Does somebody have any recommendations? I can edit CSS and HTML/Twig and touch files on the server if needed.

Thank you very much!