I am not familiar with the different Ambisonics standards.
I think it is ambisonic B format based on this.
The RICOH THETA V features multiple built-in omni-directional microphones which compose directionality from recorded audio sources, creating the four WXYZ signals.
At the RICOH link above, there is also some information about HRTF, which might be related.
I think the thread here might have the information you are looking for.
This is a relevant piece of information from @Angelo_Farina
Yes, the new firmware 1.20.1 and the new Movie Converter app create a .MOV file containing a correct 4-channels spatial audio soundtrack in Ambix format (ACN/SN3D), with correct channel ordering (WYZX) and correct gains.
The video posted in Youtube here above shows that everything is OK, now!
The issue is fixed, albeit the firmware is still saving an MP4 file which does now show explicitly the 4-channels spatial audio, hence the passage through Movie Converter is still required for extracting the hidden 4-channels soundtrack.
One would expect that the file is directly saved with spatial audio soundtrack inside the camera when the user selects the camera-stitching mode.
On the other side, if in-camera-stitching is not used, the spatial audio extraction shopuld occur inside the main Theta S program on the computer, without the need of a secondary action using the Mobie Converter app.
But for now the workflow is operational, albeit still requiring the usage of the Movie Converter program both for in-camera-stitched videos and for unstitched videos (which need to be stitched BEFORE using the Movie Converter app).
This article might also be of interest.