I did not have problems rendering when using scaled UVs on a test scene.
That said, by using a dev version of blenderseed you likely will encounter some bugs.
It will help us when you encounter a problem that you state the error message from the console.
(In Blender under Window -> Toggle error Console) so we can get a hint if it is indeed a valid bug or just some case of usage related problem.
Many times it is the use of scenes originally made for other render engines which leads to issues.
When you take a scene for an other render engine, Cycles for instance, you have to remove all Cycles specific elements from the scene (lights and material shader graphs) and replace them with appleseed ones. My guess is that your scene is a conversion and not made from scratch for appleseed and there are some elements left from an other render engine which prevents the final render working correctly.
Anyway, thanks for posting your work in progress!