The great thing is that their dnas were shockingly similar. It means the sequncing is valid. Now the ancestry composition thing is known to be a nonstandard procedure , just look at their research publications.
If the post analysis shows nearly identical DNA that's great.
The whole '% from this or that country' has to be necessarily fuzzy, because that's just a probability game anyhow.
Part of the old-school American tradition many regions (mostly rural, which is where over 80% of residents lived at one time) was to have a bunch of kids and encourage them to spread out as far & wide as they wanted; this still continues in some places. The logistics of 'keeping in touch with family' have some pretty hard limits past a certain point, and recordkeeping can be haphazard/fragile.
A great many people in North America have significant trouble tracing their ancestry back past their great-grandparents.