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.
The correction of the line of horizon, the reduction of noises, the addition of sharpness, the strengthener of the contrast and of colors.
It's my version. Not absolutely better but other.
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!