By using something like indulgences as an example, you're making a false equivalency. It's certainly possible to call it progress if you are RECOVERING from a fall. You start high, dip down, progress back up to where you were. Indulgences did not exist in the early church and didn't even exist outside of the European church when they were a thing. In that context, the recovery of what was true was not progress, it was repair.

But to imply that from the BEGINNING Christians were incorrect on something as important as sacramental theology and the role of music in sacramental theology is a completely separate claim with severe implications, as I described above.