Hi, Tx calibration does include dc offset. Calibration sets analog DC offsets which are located in:
0x05C3[10:0] DCWR_TXAI
0x05C4[10:0] DCWR_TXAQ
0x05C5[10:0] DCWR_TXBI
0x05C6[10:0] DCWR_TXBQ
What you are changing is digital dc offset.
0x0204[15:8] DCCORI
0x0204[7:0] DCCORQ