Leaks: you need pressure not volume for therapy to work. With a large leak you get lots of volume and not enough pressure. If you have a smaller leak, <24L/M on Resmed, Then you are getting enough pressure but the leaking air may disturb your sleeping.
AHI: is only accurate if the leaks are < what the machine can compensate for. If the machine cannot blow enough air, volume, to still be able to reach the pressure needed for therapy, then the AHI is unknown no matter what the meter says.
Therapy: this is the pressure that has to be maintained inside your airway and if your not having leaks and your AHI is low then you can say your treated. This does NOT mean that you are comfortable with the treatment.
Comfort: This is your sleeping time and most people have spent years and some amount of money developing a comfortable sleeping routine. Now you have added a hose, machine, mask, air pressure, maybe leaking air, stress, worry, concern on top of your nice comfortable sleeping routine. For most of us we cannot do that and just sleep like we always have and no Doctor can prescribe what settings you need. Persistent trial and error with small steps is the only way until you either get comfortable or have run out of changes and are at the best you can get.