Honestly, I don't understand why you can't.
#You should be able to see your teammate's cards and health while spectating them.
dense umbra
vital yacht
there's also a bug that swaps your health HUD when you're alive ( the image is correct but for reference, it'll sometimes often bug to make me on the smaller half and my partner on the bigger half, gets really tedious when trying to know what health you're at )
formal dock
It should be viewable.