That's all fair. The basis for the "possibly 5-C" part of the scaling comes from the ambiguity of the spirits. There might have been many, a few, etc. They might have tried to destroy the Moon entirely, or just the fruit. To destroy the fruit, they might have had to destroy the "island" (if it is the container) or a smaller, lesser container.
Personally, I think "At Most" might be better in hindsight, due to the relative ambiguity.
The Sun I'm mixed on. Like you said, LotR is widely consistent with our own universe, and the Sun should be part of it, but it just lacks a lot of the same support as the Moon. I clearly had other issues with it from checking what I wrote, but I don't remember exactly what.
Personally, I think "At Most" might be better in hindsight, due to the relative ambiguity.
The Sun I'm mixed on. Like you said, LotR is widely consistent with our own universe, and the Sun should be part of it, but it just lacks a lot of the same support as the Moon. I clearly had other issues with it from checking what I wrote, but I don't remember exactly what.
I do disagree with using the spirits destroying the Moon as a feat though. There's many of them and there's nothing that implies that it'd all be done by one guy in one blow, which means that it could easily be a feat done overtime and by a group of entities at once - which is definitely not 5-C. There's also the fact that they might just want to destroy the flower held within it rather than the whole thing.
For the record I think it's very fair to assume the sun is similar to our own given the overwhelming amount of evidence that there is for the Moon and the fact that there's some of its own, but if there's issues against that then those might take precedence.