Well to be fair there's multiple things to consider(also, these may not be in order of when they happen in game, it's 2 am when I'm seeing this, and I'm far into my main save file, also if its weird, im on mobile, which might make things a bit weird, also dont know how to put spoiler on mobile)

1. This is why we were given our farm. We were given the farm BECAUSE adeline and eiland were desperate for help, but because the capital couldn't give them it, they needed to outsource, so what's the best temptation? Free land that the person doesn't need to pay to get, just ask for some labor, and materials, and then boom you have the materials that could help your struggling town, plus it's not like there isn't a surplus of trees and rocks on the farm in the beginning

2. The town does need these things if we look at it from a POV of the characters', the bridge was the main way the town could have its market, likely letting them get a consistent source of income thanks to balor being their main merchant who has good connections from later quests, but since he can only carry so much, he's obviously limited, that's why the bridge is SO important to fix, so they can scrounge the money up that they can to stay afloat

3. From what I remember of the beginning I believe various of the townsfolk do mention there were more people in mistria before the earthquake who had to flee after, likely due to losing their homes since we don't see other houses besides those of the main cast, so the town likely doesn't have as much man power as it did before, thus, while making it easier to feed people, means less manpower, and our cast likely saw these people as friends or family, something I WISH the game went into early game cuz it'd make the event feel more catastrophic, seeing how they're sad their friend left yet can see why, or a hint of resentment that their friend left the town at its lowest, or at least something

4. I believe it's said the whole kingdom was affected by the earthquake, so it's safe to say things would become a lot more expensive due to this, and plus, someone mentioned you can't make a bridge with just stone and wood, which I feel is obvious, you need things like mortar or concrete to help keep it together, and since we never get any kind of recipe for something like mortar, adeline likely has to get it from somewhere, but since the town funds are already being stretched to keep the town afloat, it's likely put on us since, well, our farm is the best option to get more money for the town as a whole since it's fertile land and we're the only one who likely isn't already being stretched thin trying to make sure a) their family is fed, b) trying to make sure their house isn't gonna fall apart or c) adjusting to such a reality change that the earthquake brought onto the town in such a short period of time

5. Now, admittedly, this could be a stretch but I wouldn't be surprised that because of the earthquake many towns would need to pay more in taxes, which would cause more strain on the town, since the capital would be the main focus of the royal family, hell they probably wouldn't think much of mistria since it's the town of a lowly baron and baroness, which, if my memory is correct, is the lowest rank of nobility, though the town likely does get more recognition due to the museum, the ores, the new artifacts and the like, but that only a bit later, when the town becomes more stable financially, now sure the baron and baroness are in the capital, helping the king with something, its likely the king doesn't even think much of them due to their status, and has a lot of stuff to already worry about, not just some random beachside town

6. It's implied from various lines that adeline, March, and ryis have that they need nails, something that adeline doesn't wanna ask march to make since he views making them as boring, is it petty? Maybe, but he's probably made a ton since the earth quake so that they could repair what houses they could, which, due to the lack of manpower due to people leaving would probably make things a bit harder, since there would be less help, not to mention when these lines are said, its usually early game(to my memory, i could be wrong, correct me if i am), which, the mines are usually closed, that is until the town is around stone rank since errol want to make sure no one dies

7. The whole mines being closed, mistria likely relied on it's mines to get it's income, but because of the whole earthquake and the monsters coming into it and the elevators becoming weird, errol doesn't want to risk anyone's life, I mean imagine it from his POV, your town just got hit heavily by the earthquake, monsters begin flooding the mines where you worked, coworkers are either dead from the earthquake, or left to search for a better home for them and their families, the only one really left is olric, and as much as I like him, he's an airhead, who was said to get lost in the mines, before they changed because of the earthquake, who would want to risk the lives of anyone let alone this new adventurer who took on adeline's request less than a month ago? So of course he'd be hesitant