Good catch! I fixed it.
Short answer:
TL shenanigans (as already mentioned)
Long answer:
So in the final page the rank is mentioned twice:
Japanese: ト弱い職業が銅級冒険者に挑戦するつもりかよ
Romaji: To yowai shokugyō ga dōkyū bōkensha ni chōsen suru tsumori ka yo
Japanese: ...荷運び人が銅級冒険者に挑戦するなんて驚きましたか
Romaji...