H/M/L in the UNIT settings is for bell gain. While adjusting that does have an effect on the MIDI output - it's used to fix the bell not triggering at all, rather than a control for velocity curve.
EZDrummer3 does not allow you to adjust velocity curve per zone, but Superior Drummer 3 can do this. Use SD3 if you want to fix small things like this as you can use any EZX library with it anyway.
Also bare in mind, it's just as likely a bell being too loud or soft compared to it's bow it's probably an intrinsic characteristic to that ride cymbal.
EZDrummer3 does not allow you to adjust velocity curve per zone, but Superior Drummer 3 can do this. Use SD3 if you want to fix small things like this as you can use any EZX library with it anyway.
Also bare in mind, it's just as likely a bell being too loud or soft compared to it's bow it's probably an intrinsic characteristic to that ride cymbal.