that smell is purely a matter of post processing so, its can be handled relatively easily. I sued nik's SCOBy which a much milder smell, you seem to be using vinegar ones but I can probably get rid of the smell without damaging your leather much.
Water resistance is a complicated issue, with wax and oils being the most likely method, followed by calcination, but still needs to full tested.
I am also located in Brussels, so maybe we can give it a try. (my own SCOBy is still on day 5)