If I remember correctly from earlier discussions about this script, these numbers were written much later by some other owners to keep track of the ordering.
Well, since the script seems to be influenced by Arabic writings, authors should have known Arabic numbering too. But it's not clear if these are original writings, as you said, we should look into previous research.
But I am not referring to these numbers.
Here is the "12345" sequence on 49v: http://www.jasondavies.com/voynich/#f49v/0.5/0.5/2.50 (top left corner, read top-to-bottom)
Here is the "alphabet sequence", on 57v: http://www.jasondavies.com/voynich/#f57v/0.5/0.5/2.50
at least the second & third from outside circles have repeating patterns of symbols. It looks a bit like a substitiution code key to me.
For reference, the page numbering you mentioned can be seen here, "57" in top right corner: http://www.jasondavies.com/voynich/#f57r/0.5/0.344/2.50
However I have not managed to look through much at all of previous research on this document. Just sharing my thougts.