As far as infallibility goes, there are a few things to sort out. The first thing is the clear need for it. From where I stand, Protestantism (and I speak as a former Protestant) depends on a form of epistemological Pelagianism, as odd as that might sound. If anything in the Christian religion were beyond the possibility of revision, this would imply that there was some article of belief that was not a product of the human intellect and the materials that it works up to construct a faith for itself (crypto-Kantianism). If it were formally constructed only by us, it would therefore be fallible. For the Protestant, everything must meet the standard of a clear and necessary inference. The perspicuity of the Scriptures ends up as nothing more than the perspicuity of the human mind, and that is the case whether it be the Westminster minds together or Finney’s mind individually. If there isn’t a “clear” text for it, then toss it out. This regulative maxim can be anything as sophisticated as the historical-critical method or the “See Jesus Run” hermeneutic of some fundamentalists. The bed is clearly Procrustean. Protestantism is Christianity made safe for the Enlightenment. This is why in principle, there is no article of belief that is beyond the possibility of revision. Every doctrine is up for grabs, be it the Trinity, the Canon, Sola Fide, etc. Protestantism is the religion of the Raft, where every part can be changed out while one is on one’s autonomous journey. You don’t need tradition since you alone can reach up and lay hold of the epistemic merits of Christ.
J.A. McGuckin's seminal work on Cyrillene Christology remains a force to be reckoned with for those who would impugn the coherence of Cyril's Christological position. Through careful attention to the relevant texts, McGuckin systematically rebukes the notion of Harnack, Seeberg, and other liberal Protestant historians that Cyril was a crypto-Apollinarian throughout his career. Moreover, he criticizes the idea that the Council of Chalcedon represented a vindication of Antiochene logos-man Christology against Alexandrian logos-sarx Christology. The latter concept appears to have been inspired by the distinction between Alexandrian and Antiochene views drawn by Grillmeier, even though Grillmeier himself admitted that this was hardly a perfect categorization and specifically denied that the later Cyril was Apollinarian. Subsequent scholars (e.g., R.A. Norris) had sharply questioned whether the Antioch/Alexandria paradigm was meaningfully applicable at all.
I don't believe in Scotism, Banezian Thomism, OR Molinism (either the original, or per Suarez). That's part of the problem with Perry's argument. Banezian Thomism in particular is based on Cajetan's theory of analogy, which more or less everyone concedes to be a Scotist reinterpretation of St. Thomas; a similar charge could be leveled at Suarez's version of Molinism. Now that people are getting back on board with the philosophia perennis more rigorously and treating St. Thomas's doctrines of analogy, divine simplicity, and the like more rigorously, the Thomism/Molinism debate has been practically rendered obsolete as a fundamental misconception of God's metaphysical operation.
Respecting the first quote, I’ve commented on various aspects of Robinson’s argument in the past.
For now I’d simply like to draw attention to the relation between his argument and the two quotes just below, by Jonathan Prejean—Perry’s sometime ally and sometime disputant.
To the extent that our interpretation of Scripture is subject to revision, this same principle holds true for any text whatsoever, be is secular, Scholastic, papal, patristic, or conciliar, &c.
There’s nothing which privileges Perry’s dogmatic sources from this same contingency.