Seems bar Hiyya's scientific Hebrew is different from that of Abraham ben cEzra, who kinda overlapped with bar Hiyya & developed his work "along the same lines." This business reminds me of Tiramisu E telling me how there are dramatically different spoken and written/scholarly Hebrews. (Did you know that? I didn't.)
I do like when I get something juicy in section 01Axx (history of mathematics and mathematicians).