Sorry, but I can't help but read that as "it's not an imaginary line, it's an imaginary line".
She inadvertently crossed one of the most important lines that exists, a line that demarcates two sovereign countries
A case can be made that "sovereign countries" are imaginary constructs that should be abolished, along with their imaginary lines of demarcation.
I mean, I understand where you're coming from, but what I'm saying is that elevating that line to some concrete status is rooted in a worldview which has no objective reality. We can abolish borders, we just need to come together and muster up the will to do it. Which means, in part, finding solutions to all the problems the statists will use as arguments for preserving their lines.