what is it you ultimately want to do?
if you just want to get to that frame, turn on your TC overlays in the second timeline,
read the TC,
double click on the nest to pop it open,
and type the TC into the TC field, top right of timeline.
if you want to isolate the sections you have edited,
drag the nest-section from the timeline into hte viewer
apple u to make a sup clip (yes of the nested seq!)
that “sub-nest” will appear in the browser.
open it top get just the section of teh original timeline contained in the nest-section
not elegant, but it can get you out of trouble
nick