What I ended up doing is rendering a blank canvas model with a roughness of .85 in blender for each wall that I could place artwork on. Then I simply sampled the resulting colors for each side of the canvas to use in my three.js scene.
This let me get the proper hue, however I did raise the lightness values just based on my own preference. While I am aiming for realism, I modified the lightness in favor of values that simply ‘read’ better on screen, even if they weren’t completely accurate.
I am really happy with the results so far 