It's very rare to find groups and organisations that are followers of those religions. It is even hard to find a person who is aware of the existence of them, including Earth's most popular current Earth's religions (as of 2023). Many references to Earth's religions, formal or not, has made its way to being, in a way, a part of modern Piaros.
This is only relevant to Earth's most popular religions, however (Christianity, Islam, Hinduism, Buddhism, etc). Most other unpopular religions have fallen into obscurity, or, at least buried deep in archives containing Earth's culture.