The aluminum alloy will corrode when exposed to the atmosphere and elements. That is why they were clear coated from the factory.
The two part clear coats don't yellow. If you can get acrylic enamel in clear, it won't yellow either.
If you don't coat it, you will need periodic "sandings" or polishings to make it like like you like it. The frequency of upkeep will depend on what the aluminum is exposed to.
The cast parts aren't guaranteed to be without voids. So, don't be surprised if one of your "sandings" exposes a void or bubble/split in the casting.
Cheers,