@mb21, sorry I didn’t know that TeX Live hadn’t the font included (I use the ConTeXt Suite).
This sample may work with TeX Live without extra font installation:
\definefontfamily [mainface] [rm] [FreeSerif] [features=arabic]
\setupbodyfont[mainface,12pt]
\starttext
The title is {\righttoleft مشس هخصث خهس تخت تخهثز!} in Arabic.
\stoptext
BTW, I would avoid using \setupalign[r2l] unless text orientation is explicitly set in the document’s metadata.