Well Tink, I think that is a really important question, penetrating and germane... 
I actually did a bit of poking around at the time I posted all that out of the same curiosity, I never questioned it as a child...the Swedes were all doing it then, brought it from the old country, but here is what I found online:
"This dance was known in France, England, Russia, Italy, Greece and various other countries as the “Scottish,” and it would be difficult to explain, if indeed, it could be satisfactorily determined, how the title “Schottische,” which is the German form of the word, ever came to be so definitely applied to the dance as to warrant its adoption, untranslated, into the languages of all the countries referred to."
Then you find this, on the same website;
"The Schottische is a partnered country dance, that apparently originated in Bohemia. It was popular in Victorian era ballrooms as a part of the Bohemian folk-dance craze and left its traces in folk music of countries such as Argentina, Finland, France, Italy, Norway, Portugal, Brazil, Spain, Sweden, Denmark, and the United States, among other nations."
However, a couple of sources on that same website claim the dance originated in Germany...another site I found said No, the Germans just loved it but called it schottische because it came from Scotland!
...and last of all, here is the website I took those quotes from: https://www.wikidancesport.com/wiki/1092/schottische
Oh, isn't SOLVED educational??? 