Good to see you last week in Bali; we have made it home OK (typhoon in Taipei made travel tricky).
The CamDive housings are OK similar to Meikon and can work fine for most applications, you won't have access to all the functions of the camera but can take pics just fine. As long as the housing can use the lens you have it will be just fine but you can't fit all lenses.
I would suspect (they charge but don't fire) that it is the fiber cable. Take the camera out of the housing and aim the on-camera flash at the front of the strobe. Hard to believe that s&s japan didn't say they were either ok or broken and replace them. What did S&S say.
Mike et. al.
I don't think it is just social media but photo competitions as well where the winners of the macro categories are mostly big in the frame and full black background. I was impressed by Mike's photo course in Ambon where shooting macro subjects with cool blue backgrounds worked amazingly well but I am quite sure they wouldn't do as well in most competitions.
I think that there is no simple answer to how much current the strobe will draw since it it probably a constant voltage charging circuit and the current draw will depend a bit on how depleted the capacitor is after firing. You could probably instrument something to figure out the current draw but why do you really care?