Radial Blur seemed to be the most effective. I also threw 'blur more' and 'gaussian blur' at the workshop but they didn't make a huge difference. I haven't touched the area near the border. If I got too close, it smudges the black border as well.
A shot of the monastery at Sucevita for context. The paintings are too far away for detail to be discerned and the detailed painting shots don't convey the context of the Monastery buildings. What a conundrum!