I’d like to recommend Gabi! Her house isn’t technically the most autumn themed but I think her colouring is. When I first saw her, that’s immediately what she reminded me of!
I think Kiki could fit, too. Since people often connect black cats with Halloween so she has autumn vibes. The inside of her house isn’t all that autumny but I think the outside colours could work?
Either way, good luck!! This is such a cute idea