Very interesting... Someone commented on a one of OWI's facebook posts and pointed out that it would make sense for the message to be etched into the glass from the inside, making the message appear backward for the viewer. OWI replied to the comment saying that was a good idea, so that pretty much confirms that the image should be flipped horizontally before translating.
As for codes... I came across these proposed alphabets for the blind, which would be cruelly fitting. A few of them look very similar in shape to the symbols etched into the glass...
I've tried to match them up but don't know if I'm missing some of the lines, or if it's a slight variation of one of these, or if it's none of these at all.. but maybe this can spark something