So, when I was there the topic came up only very briefly in discussing the Holy Office under St. Pius X, where it was in fact permitted to hold that the term "day" before the creation of the sun, could in fact have referred to some epoch of time rather than a 24-hour period. That would not do violence to the inerrancy of Sacred Scripture, since that would just be a metaphorical use of language. There's much of that in Hebrew, since the vocabulary is actually very limited, and so they will use figurative expression, and there of course could be an etymological relationship too, where the root of the word has something in it that suggests it could be applied to multiple concrete things, i.e. where the root is something more abstract, and could indeed refer to a 24-hour day, but then could also some other specific application of the root abstract notion. So, for instance, one might use the expression that "my hour has come", without necessarily referring to the typical concrete application of the term to "60 minutes exactly".
But that was it, an implication that one MIGHT hold to an old earth, without error against the faith ... though an explanation such as above may have been helpful to avoid the impression that these decisions were arbitrary. Why is it OK to believe in a metaphorcal day, but not in a metaphorical "parting of the Red Sea" or a metaphorcal "great flood"?