thanks for your suggestions.
I have the most recent update for Acc 9 (not 10, yet!). I have export set to unicode, and I have the Syriac fonts, but I think the problem is different.
I am a novice in this matter, but I notice that even in word processors like Mellel, if you type a number verse reference: ab:cd (where each letter stands for a digit) the colon behaves as a standard arabic digit and insists on left-to-right behaviour in the midst of a right-to-left sentence. But if you put a space after the colon as in ab: cd, the reference is formatted correctly. This is standard Arabic sentence practice.
So of the double reversing that this post refers to, half is at least explained by normal practice, and can be solved by Accordance adding a space (or suitable breaking character) after the colon.
However, the other half of the problem remains: the reversing of digits within the verse, or within the chapter. I wonder whether the staff at Accordance need some help with how Arabic language formats numbers (ie left-to-right, even though their sentence is right-to-left). It is different behaviour to Hebrew in this regard.
And I just noticed another problem: when I try to copy as a citation, the book name reverts to English, despite the contrary setting.
I suspect this is an Accordance bug, but not willing yet to insist on it!