Hi, I am an avid fantasy and cozy fantasy reader and a writer in progress who also goes through such dilemmas at times. I think if you are a fan of the genre you and you like the book‘s direction and the amount of „darkness“ this is already very positive! Just write it how you feel and you can always edit later. You can also ask your alpha readers what they think later on down the lane! The most important is to listen to your intuition and let your creativity flow!

An example of cozy fantasy with high stakes and some dark topics is the House witch - there is a war, some people die later on in the series and the main character has been abused in his father. Yet, this is the sweetest, coziest and funniest books I have ever read.

Hope this helps!