Connecting CN3722 to Load AND Battery
Bypassing an MPPT controller with a diode is not a good idea, because when the diode is conducting current, it will create problems for the MPPT controller and it's power calculation.
It would be better to have a separate MPPT and BMS
The other problem is the DC/DC converter's doesn't have a cutoff, and stops at 4V so the cells will be overdrawn (and die) if there isn't any logic to shut the DC DC converter off.