gunter is right, all gecko 1.9 based browsers will display that text properly.. and eventually kmeleon when it migrates to gecko 1.9 which its release date has not been set yet, the next km 1.5.4 will still be using gecko 1.8 trunks, but remember arabic-windows encoding isn't really standard just like arabic-mac isn't. you'll notice that more professional websites like bbc arabic news use unicode encoding for their pages.. that makes their website accessible across all browsers and platforms.
that bug is very rare and you shouldn't really worry about it, in fact this is only the second website i know to have that problem it all happens with arabic-windows encoding and only when specific characters are highlighted out in different colour code. if you surf to that page frequently; i'd recommend using the ietab extension where you can use the ie trident engine inside kmeleon without the need to use an additional browser... this is what i normally do when i encounter incompatible websites.
you can download ietab extension from there:
extract the 7z package inside kmeleon's folder and remember ietab needs to register some component files so after extracting the files go to k-meleon\components folder and delete those 2 files:
and restart kmeleon.. those 2 files are safe to delete and kmeleon will automatically create them with newly added ietab components registered.
to use ietab, either right click on a page or a link and select send to>trident render or ietab
the page will then be opened in a newtab using the ie engine
happy ramdan and scripture studying