Thinking out loud here, but what are the chances that Maglev could be anglicized as Maghreb as well? Is it the same in katakana?
You know what? You might be onto something. The thing is, the author does not necessarily give us the actual spelling of any made-up loanwords, including in this case. Pair that with the reality that Latin–katakana conversion does not have a hard-and-fast rule, and what limits our translation effort is the knowledge of the author and/or the translator.
FYI :
Maghreb (a region in North Africa) is spelled as マグリブ (Maguribu)
The one in the manga is マグレブ (Magurebu)
There’s a non-zero chance that the author is referencing the Maghreb region and simply changed a syllable to make it sound different. I picked Maglev because that’s the closest match based on my own knowledge. Another translation group in the past (FableFrame) used Magref, which is also quite close.
There’s a lot of opinion involved in the scanlation landscape, but Maghreb is actually very, very close. I’d argue that using Maghrib (which is another accepted spelling for the same region) is also correct.