The world depicted in the comic is not modern, so I think the problem is not about naming things. Surely, witches and potions are covered by Latin texts, albeit not Roman. On the contrary, the style is modern. A serious translator is aware that he is to carefully rephrase the text so as to make it Latin, to render the sense in adequate Latin, rather then just look up individual words and pile them together. This is evident for us, I think, but it is exactly the impression I get from the existent translation.
For instance, we see that ‘Fantastic!’ has been translated as Mirifice!. Is this the right way? Essentially, ‘Fantanstic!’ is an interjection expressing delight and mirifice! looks like its made-up Latin counterpart. Is there no way to express delight in Latin? I believe, there is. Would Euge! do? Should it be reinforced by doubling, or by papae/-pae (I’ve got Forcellini open)? Are there options besides euge? I’m not sure.