Mike,
I find it fascinating...
Since the words "Glasfabrik Karlsbad" are really pretty generic, maybe they could not control the use of such generic words, only the use of their brand "Moser".
Maybe the similarity of the label to a Harrach label could be explained this way also.... We are going to buy Harrach blanks and decorate them. Then we are going to produce a Harrach style label to put on the underside with our marks. And since we are a little "factory" in Karlsbad (or close) we are going to state that on our Harrach style label since it may not truly be a trademark of any kind.... Then if accused by Moser of anything they had plausible deniability......
If there was a company called Tischer that there is no documentation about, there may have also been unknown decorators we know nothing of at all... until now.
Although it is a "stretch", it would not surprise me in the least.
There are references to Moser pieces with only Glasfabrik Karlsbad, and then there are references to the same mark with the addition of the word Moser. Maybe the addition of the Moser brand was in response to other labels that showed up with the Glasfabrik Karlsbad on it. Maybe they had to add Moser because they could not control use of the other two words.
Kind of like labeling something "Auto Factory Detroit", and adding Ford to it when Chevy came to town.
Why don't you send an image of the label only to Moser and see what they say about it... Crop it so the glass is not really visible and see what they say about the label only.... Maybe tell them it is on a piece of "Moser" you own and was curious as to the history of the label as you could not find it in the book they published, or any others. Ask if they have records indicating what the production marks on it indicated....
You know... kind of the reverse of what you did here.... present the label to them under the "strong assumption it is Moser", ask them to decipher the label markings....... then show them the glass..... if they ask.....
Could be quite interesting......
Craig