The Arabic appears to transliterate as S?n?’, which I assume is something like See-nah. But in any case I don't think we should be obliged to follow current native pronunciation (or spelling) of names which have been part of our culture for a very long time, e.g. names from the Bible or classical antiquity (or 'Paris', if it comes to that.)
Veni, veni Adonai!
Qui populo in Sinai,
Legem dedisti vertice,
In maiestate gloriae
No doubt you will have sung that in your youth, Rachael.