From the UI perspective, here is a bit about the RTL support T261029#6449439. There seems to be promising packages and frameworks in both React & Vue that makes it possible.

@Ladsgroup and @Addshore, do either of you have any hard learned wisdom on RTL support in features that you can share with us? I remember vaguely seeing a blog post or wiki page about things that were learned in developing Extension:RevisionSlider at some point.

@eranroz Do you have any advice on basic tooling that should be included in our new Django app to make supporting RTL in the interface and content easier?

Some good high level advice at https://material.io/design/usability/bidirectionality.html

I'm sorry, I haven't done anything multilingual with Django (and including modern frontend frameworks like React) but I would be definitely happy to test anything. I know only css janus and we have been using it in mediawiki (IIRC) and I'm quite happy with it.

Similar to Amir, I have no much experience with Django, but css janus works pretty good in many cases.
Just as a good practice, it is good to keep in mind to avoid using inline styles that are LTR/RTL specific (such as style="text-align:left;") but to prefer id/class to make it easier to define it in clean CSS than can be adapted to RTL friendly