Now that the glue has dried on the end trusses lift the roof off of your diorama building. The roof will lift off with the tin foil it may be stuck a little bit to the roof or trusses so be careful & remove all the tin foil. You may need to use an exacto knife to get into the corners to remove the tin foil sometimes it sticks right where the truss meets the roof.
If you would have tried this without the tin foil you never would have been able to remove the roof. There are probably other materials beside the tin foil that you can use for this the tin foil has always worked for me so I never really looked for anything else.
If the trusses are not totally stuck to the roof you can run a little bit of glue to the inside of the truss to make sure it is secure. A tooth pick works best for this just don’t over do it because the glue will show otherwise when you look at the bottom of the roof.
Test fit the roof now that the tin foil is off & everything is completely dry. The roof should sit on the building & remove as smooth a silk, if not now is the time to make minor adjustments before you install anymore trusses.