Your view, that "Darwinism" is insufficient to explain the appearance of all genetic variation, was also exactly the view of M.-P. Schützenberger, one (along with Noam Chomsky) of the two founders of formal language theory as we know it today; his views are elaborated on in this article (in French), although there are no formal mathematical arguments there.
Schützenberger was very much not a creationist, and does not propose anything except for the fact that the current theory is insufficient. Unfortunately, his questioning of Darwinism (whether correct or not!) led to him being branded as a creationist and his ideas therefore rejected without further question, in spite of his vehement opposition to that idea.