How to export head motion?

Hello everyone, after I connect a2f to unreal engine using live-link, the character generates nice head movements based on the audio, but in a2f either exporting the data in JSON format or USD format, it doesn’t contain information about the head movements, I found out that the information about the three curves, headRoll, headYaw, and headPitch, is obtained in unreal engine through the “Evaluate Live Link Frame” node, is there any way for me to get the values of them from a2f?