Hopefully someone else can give a more definitive answer than this...
No Sony reader to-date has been able to correctly display any right-to-left text with its stock reading app - except as a PDF.
If you have rooted your PRST1 and loaded FBReader or CoolReader I don't know whether right-to-left epubs are supported. I would think at a minimum you would need to download suitable Arabic fonts to wherever CoolReader/FBReader expects to find them.
I can say that FBReader is one of the standard reading apps on PocketBook readers. It was certainly possible to display right-to-left Hebrew epubs in FBReader on a PocketBook -- not that I read them myself, but I remember others discussing it.
My only experience with CoolReader has been on my android smartphone. It certainly handles custom fonts better than any other android reading app I tried -- but whether it handles right-to-left epubs, I don't know. I haven't tried FBReader on my phone because I never liked it much on the PocketBook, however that's just my preference not a comment on how good FBReader is.
If you have already rooted your PRST1 wouldn't it be easiest just to download and try the apps for yourself, as both are free?
Last edited by jackie_w; 10-08-2012 at 04:10 PM.