You’ve got it! The answer that fits the bill is POESLIEF.
In Dutch, “kattig” can describe someone with a bit of a sassy or grumpy attitude, like a cat. “Schattig” on the other hand, means cute or adorable. Poeslief perfectly captures the idea of something that manages to be both a little bit mischievous and undeniably charming, all in one eight-letter word.