That seems rather beside the point. There are plenty of teachings that are not "inconsistent" with Scripture that are not in Scripture: the veneration of Mary, prayer to the saints, the infallibility of the Pope speaking "ex cathedra," the "filioque" clause of the Nicene Creed, are four examples. None of these are inconsistent with Scripture, but they are not found in Scripture and thus are not necessary to being a Christian. The Catholic Church holds them, and one can believe them without doing violence to one's Christianity, but they are not necessary. Therefore, to judge the Catholic Chruch as lacking authenticity or integrity because they change an unnecessary teaching seems to me to be using the wrong stick to beat this particular dog.
Now, about Limbo--the point of your thread:
The Catholic Church's teaching on Limbo they have long acknowledged is not a neccessary teaching. It is a conclusion based on the best thought that the medieval Roman Church could develop, but it was always a point of argument. So if they change their thinking on it, it's no big deal. They excommunicated no one because he thought that Limbo didn't exist. They didn't demand it as a condition of baptism.
Your choice of Limbo to criticize the Catholic Church was interesting because it was a tempest in a teapot.