Thanks, guys, for illustrating my point: The LL rule is vaguely written and open to interpretation.
You might think that "go beyond" means one thing, but "rounding" and "overrunning" first are two completely different things, covered in-depth and differentiated in other rules, and this rule doesn't specify either.
Nor does it say anything about the batter-runner being in foul ground or fair territory. That is a personal interpretation that the rule does not address.
Thankfully, ASA addresses all of these "what-if" scenarios in their double base rules. Takes all the "personal interpretation" and "this is what they really mean to say" guesswork out of the equation. The LL double base rule has big enough holes in it to drive a Mack truck through!
Did the batter-runner reach first base? Yes.
Did she pass it? Yes.
Did she return to the white portion? No.
Should she be out? According to the rule , as written, she should be.
Absent any official interpretation, all you can go by is the rule as it is written. Anything else is just opinion and speculation.