update. it looks like one of them is trying to break out! i have concerns about the other.
in case anyone else runs into this, i read, and re-read, and read again, the assisted hatching guide on this page. humidity was cranked to 70% and as high as 90% for a few minutes once.
i got the hell pulled away around the pip that was in the bad part of the egg. eventually i settled on the following method to keep the membranes soft and pliable: i took small quarter size pieces of paper towel and used a q-tip to spread coconut oil on the paper towel. enough to make the whole thing look wet, not nearly enough for the oil to pool or drip. i used those and placed them like patchwork around the opening i made, covering the membranes. it seems to have worked beautifully. membranes are nice and stretchy and not dried out at all and these suckers have now been in this state for well over 12 hours. but they are chirping, breathing just fine, moving around in their shells, and one clearly still has veins to absorb. so we can stay like this for a while!