Unfortunately 3D Slicer does not save the IJKToRAS transform for recorded volume sequence, so you will lose the ImageToReference tracking information if you save a recording of Image_Reference. A workaround is to send the ImageToReference transform separately and send the image using EmbeddedTransformToFrame=“Image”. You will also have to record the ImageToReference transform. Using a scene with the transforms already set up is fine.
For U32 and U33, you should record/reconstruct the ultrasound entirely in Plus. The PlusRemote module in SlicerOpenIGTLink can be used to control the recording and volume reconstruction over OpenIGTLink.
This isn’t a part of the tutorial, but you might also be interested to know that the SlicerIGSIO extension can reconstruct volumes from a sequence or in real-time from within Slicer: Real-time 3D ultrasound volume reconstruction using SlicerIGT extension