I'm currently playing a 1.20.1 fabric modpack and adding this mod to it. I'm using alpha version v20.1.1159-fabric, which seems to be running fine.

It appears that the enchantment energy modifiers mentioned in the original QuarryPlus are implemented for Forge and NeoForge, but not for Fabric. And not for 1.20.4 Fabric either.

The default config doesn't seem to require very much energy, and I was trying to increase it, but the enchanted quarry actually seems to use less energy than the normal quarry 😅

You can change energy configuration in config file. Change the value of quarryEnergyBreakBlock to higher, then quarry will require more energy.
I don't implement Enchantments-Coefficient option, as it's too complicated in calculation.

the enchanted quarry actually seems to use less energy than the normal quarry

It's intended. Unbreaking will reduce the consumption of energy.