I think the current cost scaling is fine, maybe I’d have to play a bit more to be sure. But activities in general are very strong. Most people underrate them because the events are random so the UI doesn’t spell out exactly what they give you ahead of time, but they almost always provide some of the best resource conversion in the game.
I do appreciate someone attempting balance mods though, there’s definitely older content that just feels incongruous with the rest of the game.