Thanks for testing it!
The 2D Custom mode looking worse would mean it’s not able to properly rectify the image. Both modes looking the same likely means it’s not able to calculate depth and falling back to the 2D projection.
The headset doesn’t seem to provide the camera distortion parameters to correctly calculate the rectification. It would be up to HTC (and possibly Valve) to update the firmware and drivers to provide the correct parameters. Not sure that is possible without factory calibration either.
I could try adding support for using the stock pre-rectified camera frames for 3D reconstruction, but it doesn’t work well for the Index at least.