In Korean, it’s completely normal for people to address others by their occupation: e.g. teacher-nim (nim being an honorific thing, kind of like the -san in Japanese), student (an adult addressing a stranger who looks to be school age), “police uncle,” “soldier uncle,” etc. So Danbi calling Lushaka “Inductor” is actually nothing out of ordinary here.
Note, though, that Master simply calls him “Inductor” without the -nim, while Danbi adds the -nim. I wasn’t sure about putting the -nim in the actual comic dialogue since it’s not English, and I prefer to not add jargons unless absolutely necessary.