Today, I touched up the paint on the entire roof support structure and filled any gaps with spackle. I installed the attic window and ceiling trim on the second floor.
When installing ceiling trim before the roof goes up, be careful not to block any tabs with the trim. Always cut the trim pieces to match the size of the ceiling edge you are gluing them to, rather than the wall edge.
I also installed doorknobs on the interior doors. These knobs are designed for one-inch scale dollhouses, but they are small enough to fit well on this half-scale model. I will order the front door hardware later.
Additionally, I glued a back edge trim to the center back wall edge.
Finally, double-check everything in the attic to ensure it looks perfect before installing the roof panels.