No, the Gain Assist does not apply to onboard transmitter recordings. These onboard recordings are set at a fixed gain, specifically at 20dB nominal gain.
Furthermore, the Gain Assist function operates on the inputs of the transmitters, which are separate from the camera pre-sets for the RX. This ensures that each output from the RX and TX operates independently, providing you with greater control and flexibility over your audio.
For more information about the Wireless GO, please see our Wireless GO (3rd Gen) User guide.