Hello again,
Thanks a lot for your kind response! Spelling is certainly an interesting issue. There are often situations where I find it difficult to make the right choice. Also when I look at some work of great composers (like for example some works of Schuman), I cannot always understand the reason for some of his spellings. Therefore it is so nice when people provide me with alternative opinions and explanations. I can see that your two suggestions for MS 179 are certainly possible and legible. (I would probably prefer the first one). Also, I agree that the flats in MS 180 should be bracketed, but maybe it becomes a bit messy (at least for sight reading), and this would be another reason to go for flats in MS 179. Altogether, I am very grateful for your engagement! Thanks a lot!!
(In the meantime, I wrote the second movement of the sonata. I will post it as well and I would be curious to find out what you think of it.)
Best regards