how "Firenze" might mutate into "Florence" in an English mouth

It was Florentia before Rome fell, then Italicised to Firenze. It's arguable that Naples is nearer Neapolis than Napoli is. It's astounding how names persist- Nablus is another Neapolis, despite Byzantine, Arab, Norman, Ottoman, British and Israeli occupations (I almost forgot the Mongols). And London is still London, despite Augustus.