Interesting. Not only rye-based distilling comes from (some) German-settled parts of Europe, but now wheat-recipe too. What's next, the charred barrel originates in Cologne?
But seriously, that is interesting data, gents.
Genever gin always used a base of malt and wheat and/or rye: later corn was used as a component. Dutch genever was often (not always) flavored with juniper. Alsatian spirit was made and still is from fruits and evidently was also at one time from grains. Perhaps it was flavored with fruits in the home-country - a clue may be the fruit-based whiskey cordials and cocktails that took root in America.
Swiss people clearly too used various grains to distill.
But Scots people used mixed grains too. Wheat started to be used with the Scots column stills (still is). In the later 1800's, column distillation was common in Scotland and parts of Europe.
The important thing to me is, most of this spirit would have been unaged or little aged. So, it wouldn't have mattered really where the specific influence came from because it was not necessarily that distinct in any of these places. (Only towards the end of the 1800's did well-aged single malt whisky emerge as a separate style for example and on the Continent they never did age grain spirit systematically: to this day the German korns and Dutch genevers are white spirits, basically).
I think what may have happened is, in Alsace at the time, a primitive form of column stilling was being used and wheat was well-adapted to it. Wheat can create some fairly pungent fusels but this would not have mattered considering the relatively high proofs deriving from the column still.
So in other words while interesting, I think at most it suggests that new ideas from European distilling - drawn from different parts of Europe in different ways, e.g., through books, immigration of distilling families - influenced American practice. But the influences were not (I think) unique. F.X. Byrn in his 1870's book on distilling refers e.g., to the highest quality of genever being made from wheat (this referred then to Flanders and Northern France). These ideas were "in the air" at the time.