That party leader guy should just go be a soldier if he thinks they should fight to their last with only their own supplies, obviously they need to keep some for emergencys like running the fuck away.
A verbal promise from a guy that isn't even the lord of the area about some unspecified rewards? This is such a shit deal it's crazy.
This MC is a complete shitter, it starts out with him like "hey I question this" miracle bullshit gods approve and then he just runs around being a complete fool, suddenly magical hidden fairy, but he's too retarded to try to reproduce anything from the first summoning, see you in a thousand years when MC grows a brain, fairy.
And this guildmaster guy, what is he doing? He's running a branch of an orginisation as big as or maybe bigger than the country that without the country would absolutely collapse by moster overflow, how does he not have a hand over whatever the fuck the lord decides already? Just look at real life, any time a big corp goes unhappy some politican has to go and make them happy again, mostly because they don't want to lose taxes, but also because there is no such thing as a clean politican.
There's also the brainwashed party, why is that even in the story? It feels more like the author put it there because he read another isekai that did something similar than anything, they seem to be using their time better than MC but they couldn't be stronger than MC because MC is MC, makes it even more obvious how MC is just loling around.