That looks decent now. There isn't much you can do with classic roofing. The grey castle stone and the sandstone provides angled pieces that can imitate a roof, with a similar stone inside for flooring to blend. I'm don't believe either would look very good on that house, however. You could try bumping up items to make a roof - barrel slats or nets from fishing, opened bedrolls, layered cloth, etc. If you try that you will need to remove the rail, temporarily at least. I'd also add in tall wooden corner posts so it looks like they are holding up your false ceiling.
If it was me, I'd fix the top front corner - the edging on the corner needs to be added with the piece beside it as the window does below it - and then leave it as it is. It looks nice.