What will be used are the understandings of the various ECFs who do not see this issue as Rome claims.
This is why the opinions of the ECFs are not to be held to the same standard as inspired Scripture.
True of isolated "opinion". But the consensus of the Fathers is the only way to interpret Scriptures if what you're looking for is the lived continuity of understanding and practice.
Having native premodern Greek-speaking language fluency, and being immersed in the prayer, practice and culture of late-antiquity Christianity, they were much closer to the NT texts and ways of life and worship than, say, a committee of German-speaking skeptics 2,800 miles distant and a millennium and a half later.
It's like asking, Who could tell you more about what the Civil War was really like? Actual Civil War veterans and their sons, or 21st century Civil War re-enactors and their sons?
So --- if you prefer, I'll state it differently --- did any Christian say that Catholic communion in the Body and Blood of Christ conflicted with, or was contrary to, the NT until the 16th or 17th century?
Even as late as the late-15th century (Bohemian Reformation), the "reformers" saw the Eucharist as Christ's Blood, and stated it in those terms.