ADC Calibration in ADuCM360

I would like to use a Whetstone bridge load cell as a sensor, with 2mV / V gain.

The supply voltage of the cell must be 5V, therefore the value of the voltage to be measured will be 2.5V +/- 10 mV.

If I have not misinterpreted the indications given in the datasheet and in the application notes using an external reference voltage of 2.5V and enabling the two buffers the device's operating limits will be respected.

I have not found any indications for determining the maximum offset interval that can be corrected with the offset calibration.

The document UG-367 reports that LSB weight = 2 × VREF / 49150 = 48.8 μV and that the valid range of the ADCxOF register is 0xA000 to 0x5FFF (-2476 to 2475) so it would seem that the maximum interval is equal to +/- VREF .

But from the measurements I made I get that the maximum offset range that can be corrected is +/- 6mV.

What limits the maximum applicable correction value?