Daria, id leave things be for a while. Ahi under3 is great.
IF he can stay with nasal pillows or mask do.
If he goes ff he will need more pressure. I do on ff and so does wife if either of us has to go ff. I started ff went nasal and use 4 to 6 cm less pressure.
I have that machine. The spikes are what you said and are only .5 cm to 1 cm depending.
As long as total leak is under 70 your good to go.
Cell phone limited data Daria lol.
Aflex may be smothing him at times on three. It lowers pressure at top of inhalation.
Also regardless of setting it will only end exhale 2 cm below current pressure. Then based on previous breath it will build to current pressure on inhale.
You nan run that machine on cflex in auto mode as well. It is a straight pressure relief 1 2 or three that is full pressure until exhale and full pressure relief per setting but is at full currrnt pressure at end of exhale unlike Aflex.
He might like cflex better.