In the ManwhaFreak translation it was left in Japanese. I guess that, in both cases, the scanlators decided to forgo translating from their raws, with this group using Vietnamese raws.
By the way, “magus” is just Latin for magician. The Latin comes from the Greek “μάγος”, with adjectival form “μάγικος” [“magicos”]. So a “magus” rank amongst magicians is silly.