Talking to the HL series through UART/AT commands is obviously the only way to work with the unit as this is the primary interface. As I say the HL works with the mangOH boards because of the CF3 (common flexible form factor) strategy but is not optimised for it hence no connector on the board leads to this interface.
MangOH was always designed as a tool for developers to tinker with the WP and is embedded processing capabilities and produce PoC’s quickly, not as an entry level dev kit although several people can use it like this, as you are, but there are limitations.
I think mangOH yellow is better than red in this respect but I have not explictly looked/got one myself yet.
Regards
Matt