I am also completely lost with this!
I've had examples of several designs, including items with no satin effect on the foot.
I've compared the 'fake' and the 'genuine' (defined as above) and it is really hard to tell whether there is any variation in the pattern at all! The mould would seem to be identical, and the only 'diffentiations' are the sort of thing you find comapring ANY two objects of the same design (air-bubbles in different places etc.)
It seems apparent that we will need to help ourselves along by trying to get a detailed overview of the (very small) variations which cause the authenticity to be questioned.
The three factors to keep in focus are
1) is the item satined all over (including the foot) or does it stop where the figure section is covered by the frog?
2) Is the height identical (there seems to be a possibility that the 'fakes' are very slightly smaller!
3) Is the item accompanied by a frog from the right Walther period/Does it match with a Walther bowl (e.g. colour)
I examined the two shown left of picture, and was surprised that there was almost NO(!!) perceivable difference in the moulding. Perhaps naievely, I expected the 'copy' to be a little 'blurred' , but couldn't confirm it with my eyes.
It also seems reasonable to wonder whether the genuine moulds may have moved factory in later life, or whether a second period of production took place without being catalogued. (Both of these are well-established events in the history of other similar factories)
Iron moulds for pressed glass were considered part of the 'design asset' and companies which stopped production often sent(/sold) the moulds to a continuing glass factory. (Their value, like the knowledge of how to use them also disppeared with surprising speed once factory was closed!)