Your description of the shunt wiring is hard to understand. The battery negative goes to the battery side of the shunt and is the only cable on the battery and that side of the shunt. Everything else goes on the load/system side of the shunt. This is for battery monitoring.
In terms of has DC system, do you in fact have chargers and/ or DC loads. This FAQ explains about the vageries of has DC system, it will count things like idle current for the inverter, Cerbo GX etc.
To get an accurate value here needs a SmartShunt used as a DC energy meter.