As far we we know they were never within the RCC. Correct me if I am wrong.
History is full of woes and sorrow , yet The Light still Shine . It is very interesting how we acquired much history upon the RCC and her decree's . How she tried to destroy so much truth of God's people , by taking there lives with the sword and fire . Yet there are trustful historians , even those of particular movements that had The Light and share it with others so that they can be freed , in Christ and destroy the works of the devil.
Henry Arnaud , one of the most intelligent of the Waldesian pastors " Neither has there church ever reformed , " say's Arnaud whence arises it's title of evangelic."
The Waldenses are in fact those refugees from Italy , who , after St Paul had preach the Gospel abandon there beautiful country , and fled , like the woman mention in the apocalypse , to these wild mountains .
Book Title : The Waldenses , Sketches of the Evangelical Christians of the valleys of Piedmont pp. 28 , 29
So you are correct that they never were Catholics , there were many other sects as thee waldenses that continue to preach the word of God . But the reality is many of these books are out of print . That is why not many believers are getting there history .
Shalom