So what basically happened in case future readers are confused by the translation:
After putting the [Shell Crab] in frenzy mode with it foaming at the mouth and running away to heal, Tsutomu seemingly suggests that they back off to go check on areas it wasn't heading first then to go and check up on the trap later to see if the [Shell Crab] fell for it.
Amy and Garm,both initially being frantic and hasty want to go after the [Shell Crab] directly instead in-order to finish it off before then, making Tsutomu realize that they were both too worked up to think clearly and assess that their main purpose for fighting the [Shell Crab] was to find out its hiding place via a trap first.
Garm gets talked out of it by Tsutomu, initially citing Garm's potion use for the day as an incentive to stop early for the day, which Garm then seemingly proceeds to say that they weren't in God's favor today to beat the [Shell Crab].
Amy promptly disagrees with this sentiment saying they wouldn't get another chance like this, as a 3-person team, showing she still deep down holds the sentiment that they are very 'LUCKY' to have been able to push the [Shell Crab] this far and that the trap idea wasn't going to work anyway because 'no one else' or 'top guilds' have been able to do it. Showing further how much lack of faith she has in the trap plan, and directly/indirectly Tsutumo.
Tsutumo notices this, but wants to de-escalate the situation, until Garm ignorantly remarks that it may have just been Amy's previous clan that wasn't able to go through the plan hoping she would emphapthize with this sentiment because Garm's previous clan was also unable to do it too.
Amy, obviously taking offense to that sentiment that the clan she was previous a part of was at fault indirectly saying she was also incompetent because she was a part of the clan, then proceeds to personally attack Garm, and then ignorantly maybe the trap might actually work since they have "LUCKY BOY!" on their side.
Garm is obviously aware at this point of how much trouble this moniker has been been for Tsutumo and gets super pissed at Amy, because she was basically not acknowledging Tsutumo skills after-all this time of partying together and was acting no different if not beneath the "surface dwelling insects" who hung around Tsutumo.
Tsutumo at this point, was already aware more or less that there was something a bit "off" about how Amy acted around him, but hearing outright from her made him snap a little on the inside. He wants to be taken seriously for his achievements and even though he's been working with Amy to change her mind about his usefulness as a person and white mage, Amy only saw a "LUCKY BOY!" who had unique skills {flying heals & enhancements} who was favored by the God of the Live Dungeon.
Taking this into consideration, Tsutumo then proceeds to treat Amy on only a professional level, joking about her using his moniker as "LUCKY BOY", and then directly moving on to business as usual. Not putting in the effort to correct her or change her mind, because to him then Amy was simply a "hired party-member" not someone like Garm.
