What do you think that means? Martell's indicated he was truthful, but Brooks-Murray's indicated she was truthful when answering specific questions? Does that mean she was only truthful part of the time? And Daniel was all of the time?
I think it means their mother was asked some questions that triggered a different physiological response than others, along the lines of (paraphrasing):
Hypothetical Question [Q}: Do you know what happened to them/were you involved in their disappearance?
Hypothetical Response [R]: No, I'm so torn up about it, and didn't do anything!
Hypothetical Q: Do you have any potential suspicions or relevant knowledge about who may have been involved in their disappearance?
Hypothetical R: No...., ummm, no...., I can't say because I don't know...
I did a deep dive into this (reasons why during polygraphs tests, people could respond differently to different types of questions asked) on a website which offered an "official" narrative about it, and it was pretty much this, so I decided not to post a link and get into it because it's "just an investigative tool" afterall.
Paraphrasing again, it suggested:
Straightforward questions related to specifics were often easily answered by the subject with no or an appropriate physio response recorded.
More general or overarching questions were less easily answered with a different or less appropriate physio response recorded. Perhaps due to the fact that the subject may have been still uncertain, still processing, still in a traumatic stress response, still trying to figure out what may have happened (and still wondering if they could have done something to prevent it happening, e.g., feelings of guilt or shame or culpability because they were not aware or able to prevent it at the time).
It's a bit of a rabbit hole to go down, I trust LE knows what they're doing, and am not questioning anyone's results or interpretation thereof, but pointing out some questions they asked Lilly and Jack's mom may have been triggering in different ways, as to why some of her physio responses to certain questions were redacted.
JMO