The problem is your walls and floor materials have reflectances much greater than 100%, as the spectra are in percentage rather than fractions as they should be. The simple fix is to change each material definition from something like:
void spectrum spectra_floor
0
0
22 380 780 11.32 29.49 42.63 45.8 48.01 49.62 50.9 52.69 53.84 54.99 56.31 57.27 57.89 58.33 58.63 58.81 59.06 59.47 59.64 59.64spectra_floor plastic floor
0
0
5 1 1 1 0 0
to:
void spectrum spectra_floor
0
0
22 380 780 11.32 29.49 42.63 45.8 48.01 49.62 50.9 52.69 53.84 54.99 56.31 57.27 57.89 58.33 58.63 58.81 59.06 59.47 59.64 59.64spectra_floor plastic floor
0
0
5 0.01 0.01 0.01 0 0
In other words, you can continue to cut-and-paste spectra, but be aware when they are in percentages rather than fractions. Your first example with the window glass was fine, which is why I needed to see your other files.
Best,
-Greg