Milwaukee would be a simple train journey for the Archive as presumably she is subject to the normal mortal wizard fudge factors ruling out air travel, and her neutrality ruling out travel via the Ways largely controlled by Winter and Summer. Nick would have taken this into account.
I have doubts about both of those, actually.
The tech interference is said to arise from mortals being inherently, internally conflicted. Ivy might not have the detachment thing going as well the ideal paradigm of an Archive host - who basically wouldn't even have a personality - but she's still way more detached than most wizards, meaning less to be conflicted about. She probably would have been a problem for airplanes *after* being captured and tortured, but not necessarily before.
As for the Ways, it's possible her neutral-by-nature status means neither Winter not Summer would take it as an insult to their nation if she passed through the Ways on their territory. She might not have the Queens' guarantee of safe passage like the Council had from Mab, prohibiting any predatory fairy creatures from trying her, but it's not like mook-tier predators are a real threat to her.
