To add to this discussion, it's not just RTL support, but also support for complex scripts that's currently missing.
If I paste Hindi into Affinity Publisher, the letters don't appear in the correct order, notably in the word Hindi (हिंदी) itself!
If I type Devanagari k-virama-r, the virama remains visible and the 'k' and 'r' don't combine as they should
However, there is some contextual shape-changing already present: if I type in Arabic bab (باب) = door, the first 'b' correctly changes shape, but incorrecly stays at the left end of the word.
I appreciate there's more work to be done, but as mentioned above, surely it's better to build in support for non-Latin scripts early rather than nail it on later (InDesign) or not at all (Quark).
Good luck