I believe your numbers may be close to accurate.
They will come back to the mother church!
Sorry to burst your bubble friend, but when a Catholic finds a Bible-teaching, non-squishy evangelical Christian church, they rarely return. That includes me and many, many other friends.
The ones who return to the “mother” Church are usually those who spent a number of years without a church, period. But those who become a Christian, and study the Bible, and immerse themselves in the non-Catholic manner of worship and study have their eyes opened. They never look back.
Doubt they will ever come back. They want to go where they can be fed on the spiritual level.