Using the definition of superstition as cited in my previous post as a starting point (I don't agree with it, BTW), there is no more reason to consider a combination of Scripture and tradition (as defined by Roman Catholicism or Eastern Orthodoxy) to be any more factual than sola Scriptura. The fact that, for example, the Council of Chalcedon defined the Second Person of the Trinity as being "wholly God or wholly man," does not make it an observable fact. It is true that this council defined the doctrine, but their definition does not make the doctrine true. If you assume that the members of this council were divinely inspired, then the question arises as how you would prove that they were so.
Both sola Scriptura and the Scripture/tradition position are objectively unprovable and thus, assuming the definition is valid, is superstition. Ultimately, it is a matter of which position (or for that matter, the position of Jews, Mormons, Muslims, Buddhists, atheists, etc.) comports with one's presuppositions and which position is more reasonable, that is, more in agreement with observation and reason.
Both sola Scriptura and the Scripture/tradition position are objectively unprovable The ability of the Church to refine, define, and explain the Christian faith are scriptural and historical facts. Sola Scriptura is not.