You are correct
You are correct, a District without geographic borders defined by language; I believe that the "Slovak Synod" was similar in that it was language based rather than geographic in nature.
We have one very close to where I am, Grace Mitchell. Their Pastor is LCC. I did a little research and it seems there are 12 ED congregations in Canada; all in Ontario.
Churches | The English District - LCMS
It is nice to see another Canadian here!!
Mark