Cézanne’s manner of painting, whilst it is quite evident that he employed little ‘taches’ or segments of color-form that together compose the whole. But these segments are not curvilinear, as far as I can tell.
I can think of many other good examples, which have the added bonus to focus on a genealogy of modernism (which I think it’s at the center of your research question) that takes us away from the received one that starts with Cézanne. Suppose you were to focus, instead, on the French movement called “Orphism,” and associated figures such as Apollinaire, Sonya and Robert Delaunay, Paul Signac, the chemist Chevreul (who developed a theory of color; in fact, I think that color should also be a factor in your study); that in my opinion would be a much more promising avenue, because it will shed light on a lineage of modernism that is not often considered in the usual narrative. That will also take you to examine abstraction and spiritualism, for example, in the artwork of Hilma Af Klint (who is having a retrospective at the Guggenheim just now), who used the circular figure in almost all her paintings; the works by Kandinsky from the 1920 and ’30s; examples of Russian “Cosmism,” and the relatively unknown branch of spiritualist art from the Baltic region (Lithuania, Estonia, etc.) – see in particular the exhibition catalogue from the Musée d’Orsay from last summer.
Even Van Gogh would be a better starting point to illustrate curvism than Cézanne (all his work has a sort of sweeping circular motion to it).
Finally, you should look into historical precedents, such as the “serpentine line” which was considered a trait of beauty in Italian Mannerism and later in Hogarth (Treatise on Beauty). This will give you a historical as well a theoretical underpinning. I also recommend to look into the writings by Henri Focillon, Hubert Damisch, and Merleau Ponty, of course (there is much in this idea of the curve that has to do with embodiment). Rudolf Arnheim is also an author you should look into (and the whole Gestalt philosophy movement).
Finally, you should start compiling a list of texts that are more closely related to the topic at hand, to see where the gaps and the blind spots in the research are. Keep it up!