good sleuthing - IMHO there is a more than 50/50 chance that the importer, in London, was Loebl/Lobl who, prior to 1918 and before the advent of Czechoslovakia, was bringing glass in from Rindskopf in Germany - and possibly other Continental sources.
This not really not my area - did Rindskopf become Czechoslovakian after 1918, and go on to make pressed glass in the main?
your correspondent from five years back is obviously correct, and you can't relate a silver date to a glass date exactly - and it's always possible that such pieces might have sat on a factory shelf for twelve months, but it's true that it will provide a close enough date for our purposes.
The décor on these vases does appear to have a art nouveau appearance, so the date letter of 1911 looks to be reasonably accurate.
You may not find a definite provenance for Rindskopf, unless someone comes up with a catalogue page showing this pattern/design.