Nice to meet you.
I have 2 thoughts regarding Bach and Visual Art:
The first one is that yes, the paintings mentioned do seem to be inspired by relationships and ratios, numbers etc. which I believe Bach was very keen on even in his free time. He was most certainly the master of the Fugue, insomuch as he is recognized as being so by most talented composers etc.
The Fugue itself is a form created by a collective effort spanning generations.
The other, which pains me from time to time is that Bach's music, being indestructible music, is therefore seen as something to be adopted and interpreted by following modern ideals and morals..
I have this feeling that the people who teach this stuff love to take old art and use it to push their own ideals and idioms.
You can play Bach on a simple Computer Sequencer with Synthetic sounds and it will still sound impressive.
This does not mean that the music was created to be played through 'metronomic 'absolute' interpretations.. far from it I think..
I partly deduce this from the paintings and decorative work which was created during Bach's lifetime..
There are NO straight lines in baroque-period art. There are no straight lines anywhere (other than poor people's homes) prior to the late 1800's
ANYONE can draw a straight line, and a straight line does not express individuality.
Baroque art is full of elaborate and intertwining decorations, the decorations are quite elaborate.
Furthermore Baroque art was 'finished', in the sense that everything had a craftsman-like sense of completeness, and attention to finish and appearance which went beyond rough form.
I believe that though the foundation for Bach's music is to be found in the 'music of the spheres', mathematical relationships etc. it is all an expression of god to him.
and this is why I find that the human qualities of voice and identity in the separate voices need to be part of the music.
Back to paintings, I find that in comparison, most modern art is a rough outline or sketch, which fits-in a bit more with the modern way of approaching life, religion, morals, love etc.