Keeping "the letters will still be split, but the right direction" isn't suitable for Arabic glyphs based languages because as I said they unreadable even if they appear from RTL. Arabic glyphs have to be attached not splitted this is essence rule.
Well. I don't see anyone who would try to fix the gramps34 code for this. Gramps34 is based on GTK2 and a different drawing routine. A developer who tries to fix that needs to work himself into deprecated technology.
The fanchart in gramps 3.4 is not a well developed view, so that not working is not a big issue. In Gramps 4.0 the fanchart has many new features and usability improvements.