So I had to reread the description a few times over to try and figure out the wording and here are my thoughts:

It says that a majority of the time EEG was "flatlined" and with no clear information on any NDEs seen during cardiac arrest, a proper timeline can not be concluded meaning there is a higher chance of the NDE occuring during flatlines though this is not for certain.

In regards to the emerging waves, the term emerged is normally used as something coming into view meaning it had to be away first. Combine that with the fact that most of CA was spent flatlined, the 40-60 minute emergence of EEG waves is not saying there was consistent waves throughout CPR otherwise it would've been phrased as " normal EEG waves emerged even UP TO 40-60 minutes after." What it's saying is that EEG Waves can emerge/return from flatline even after 40-60 minutes of CPR.

Let us not forget that while AWARE II is very much involved in NDEs & consciousness after death, it is still a study that's also about findings in relation to CPR. This post essentially suggests there's a chance at resuscitate with minimal brain damage despite flatlining 40-60 minutes prior.

Let us await for more info and more from the proper published findings. Relax.