Um maybe bc they are being professional
They sound stiff, why not put their first or last name after the Esper, Guide or Mentor. Eg Esper Lizzy
Probably bad translation/localization (not complaining tho, its free)
They do half the time, at least in the officials
No it's the same in officials too
Why do they only call each other Esper, Guide and Mentor and not mentioning their names