I don't think I've heard this use of consumption unrelated to writings from 100+ years ago! I agree that the word comes off slightly odd to my ear but find it sufficiently descriptive. If Kagi intends to build this tab out with more stats, perhaps something like "Usage" or "Search Costs" might sound nicer? But I've no strong feelings either way.
With that said, this new settings tab did its job perfectly in helping me understand how much exercising some custom lenses actually cost Kagi last month. Now I feel a bit bad...