Hi Downunder,
I would expect a CFI in HGFA would take into account your flying experience and train you to a level of competancy whether that takes 15, 20 or 30 hours and at their discretion charge less if doing less. There is I believe (may be wrong) a mandatory set number of minimum hours in a Paraglider before moving to Powered Paraglider.
The same with RAA, if you come to aviation and lean to fly PPC (or fixed wing) than the rule of thumb with RAA is 20hrs depending on your ability. If you already hold a Group A certificate (Fixed Wing) and wish to take on Group D (PPC) an endorsement may only take 5 hours again depending how long it takes you to reach a level of competancy. If you hold Group D and wish to get into Group A than you may be up for at least 15 hours due to the necessary learned skills to fly fixed wing.
I hope that is not to confusing.