Re: medical texts discussing eunuchs, I work only with the Latin tradition. But in terms of what was translated, both al-Zahrawi (d. ca. 1013) and ‘Ali ibn al-’Abbas al-Majusi (d. 982) discuss castration procedures in the surgical sections of their texts.
My brief discussion of the issue can be found in Monica H. Green, “Caring for Gendered Bodies,” in Oxford Handbook of Women and Gender in Medieval Europe, ed. Judith Bennett and Ruth Mazo Karras (Oxford: Oxford University Press, 2013), pp. 345-61, available on my Academia.edu page.