The only thing I've used waxed paper for in relation to quilting is ironing over it to set crayon coloring on blocks. Works great!
The crayon colored blocks lasted for years until the background muslin gave up of old age and hard usage. Some of it had been done by my mother and her sister before my mom got married in the 30s and I finished it as a home ec project in the 60s. Retired to display only in the 90s and destroyed by fire when our house burned in 2000. Colors were still pretty even after 30 years of washing.