So first things first, to clarify, an “Uncomfy” is not a comfy. They’re monsters. They are not born from the Flame of Passion and are instead spawned from negativity and the eternal dark. The word “uncomfy” is a colloquial, kind of joking and unscientific term for them, they’re more often referred to as Shadows or Creatures of the Dark. They are something entirely different to Corrupted Comfys, which are Comfys who while undergoing significant amounts of corruption, instead of becoming fully consumed by it, ended up adapting certain traits to survive and cope with it better. (A process that typically isn’t voluntary and is often permanent)
Second! Wishes do not have to be objectively “good”, however they do have to positively benefit a partner for it to be viable. Because remember! If a Comfy’s partner is miserable or otherwise suffers mentally and/or physically, it would in turn affect the Comfy negatively as well. So a person wishing for someone else’s death excessively may have their wish recognized as an unhealthy path for them to take, and will in turn not manifest.
But the good news is, you can definitely make evil Comfys! They 100% exist (some folks just take comfort in awful things). They just would not be considered corrupted, because corruption does not mean “evil” the same way it does to us in Comfy terms. It is a state of distress and pain physically manifest and is inherently harmful to a Comfy’s health (like poison).
Hope this helps! (Feel free to ask for further clarification if needed)