First, regarding the table editor: This is already in the works, although very slowly because the entire core team is currently a bit busy with personal things. But it's coming.
Then, regarding the RTL support: The thing is that CodeMirror does apparently some smart things in terms of RTL, but since I just implement that editor, it is sometimes a bit difficult to understand how I may be interfering with this.
I believe a great start would be to just have a rough overview over what the state of RTL support in Zettlr is right now; ideally with some screenshots and videos. (The latter help exemplify how you'd actually work in such an environment, which actions you perform when, etc.)
Then, we could think about what exactly needs improvement, how, and maybe start putting together a test suite for that.