When the item has a MUL label and does not have a localized label, the HTML fallback label is always

<div class="wikibase-labelview wb-empty" dir="ltr" lang="mul">

Note that "mul" is not a language code recognized by the browser, so the font used will be likely incorrect. Also, the text direction "ltr" is enforced even when it should be "rtl".

I propose that the lang attribute should be the corresponding language. For example, if the "mul" label is used as a fallback of "ar" label, then the HTML should be

<div class="wikibase-labelview wb-empty" dir="rtl" lang="ar">