I typically swim 3 miles twice a week and utilize a breathing technique where I inhale through my mouth and exhale through my nose.
This is typically of breath training for exhaustive exercise. I have this so imbedded in those little gray cells that I when I wake up I am always inhaling thru my mouth and exhaling through my nose.
I always go to sleep using the DariaVader tongue technique breathing through my nose but at sometime during the night habit takes over.
How many mouth breathing variants do we have in the forum and what kind of impact odes this have to our therapy.
I don't think what you are doing has any negative effect on your therapy, here's why.
The objective of CPAP is to maintain a positive pressure in your airway. When your mouth is closed, the pressure is just fine. When you only inhale through your mouth, air is going in and not out so the pressure is still fine.
Mouth breathing with CPAP is when you open our mouth and air escapes, causing the pressure to drop below therapeutic levels and this is not what is happening with you
I have no idea how you do it, but don't see a problem with it. Your machine should also not flag it as leaking, if what you describe is actually what you are doing.