If you make the interior of the house 1 block deeper while keeping the exterior it will solve the problem. Put the house floor on level with the path. That way they will stop using the windows.
No need to change the design, just add a small block or object at that corner where he landed, to block its path, so it will not try to jump out of the windows, as there would be no path.
He used that windows because all others are blocked by the plants. That corner window though offers that diagonal block space as path.
Sorry, checking now I see that its hitbox is just one block high, it is like a simple block piece there.
So one way to block them without changing the design is using the debug tools and raising the hitbox of the planters, so they block the pathes. (although very time consuming)
I think windows treated as portals also helps when building, to prevent hearthlings getting stuck and allowing for more paths with the scaffolding. But I agree it’s kind of annoying to see them using windows instead of doors.