Thank you. If the source is correct, and I have no reason to doubt it, the Founders were operating on bad information. Napoleon wasn't the "first successful foreign invasion" of the Confederation, unless we're being cute about how the HRE was organised.
As the joke goes the HRE was none of the 3.
As for a source on the history of the confederation: https://youtu.be/OpA_ET9bYGY