I agree with the black bar. I think you're exactly right that it feels a little out of place, but the cut-in itself is what really is breaking the scene, so I think having the black bar simply goes along with it. At least that's how I see it. I love that you added something to it, instead of a solid color, but it makes me worried about how many more of those there are and hope you don't feel like you have to create a background for each one. I love the path for the adventure
I'm struggling with what my mind is seeing and how to actually say it. I really wish I had any skill with drawing to show what I'm thinking. I also think it would be fine to simply color the stickers and either have some form of neutral color for the background or keep it white.
Unfortunately I'm just wasting space saying that I think either way would be alright.