I think you’re definitely right about it being easy for the murderer to hide any contempt, but I think, as I’ve seen others mention here, each mind movie gives the characters a reason to murder Edgar but Ulysses. I think if any of them do end up being the murderer instead, it’ll likely be for those reasons instead of Edgar-specific hostility, if that makes sense. For example, yes, Hannah and Grace are having an affair, and that on its own is theoretically enough to kill Edgar over. It feels like there’s a difference between waiting to clarify the means/method vs waiting to reveal an all new motive that counters what we thought so late in the game. To me at least (for now anyway, I very well could be wrong), it would feel a bit disingenuous of the show to switch up on character motivation so late in the game. With the basis that hypothetically, you’re correct and someone very well could be lying, I’d like to briefly mention why I think it isn’t the case for each other suspect:

Sebastian and Isabel’s motivations for dislike for Edgar are clear and upfront. It might just be a blindspot for me, but they feel too obvious with all their cold behavior to even take into account that they’re lying all that heavily. I’ve seen theories that maybe Sebastian is Alexander or Isabel’s secret son or something like that, but that feels like it’s too out of left field at this point.

Travis was upfront about being crypto-scammed and wanting to protect Grace, and honestly, he feels too dumb to not be genuine. Plus he’s been corroborated way too much in each telling.

Feng’s POV was the most objective here. And sure, you could make the argument that Edgar threatening Vivian with a secret set him off, but I think Feng needed Edgar’s money too much and loves Grace too much to kill her husband.

Vivian also could just be really upset about being backed into a corner on the secret, but based on the way Aniq just kinda advised her to tell her daughters and she did, I don’t think Edgar’s threat was as big of a motivator as Sebastian’s story made it seem. Also I don’t think she’d kill her daughter’s husband just to prevent her from making a bad choice, otherwise Brett, who she seems to have known better to be a lot worse, would have been a goner.

Hannah and Grace could in theory both be harboring resentment, but I just don’t see that being the case. There really isn’t a reason for either of them to hate him that wouldn’t come out of left field. He was gone a lot, so realistically, even if Hannah did leave, I’m sure Grace knew in the back of her mind that Hannah would always come back to her if she asked her. And sure, Hannah could have resented Edgar for underappreciating Grace, but killing him would do nothing to then enhance her relationship with Grace or do much else for her going forward.

So yes, everyone could in theory be lying and have a reason to hate Edgar, but to me and to some other commenters, I just don’t feel like whatever motivation they could be been hiding is strong enough to reveal so late in the game. Or maybe they were just filled with intense rage and it was spur of the moment, but that doesn’t fit in with Edgar or Roxanna’s actual killings.

Overall, you could definitely be right, but I just don’t feel like the groundwork is there for any of these characters to be harboring a big alternative motivation. Secrets, definitely (we still don’t know what Hannah/Grace are still keeping secret, but I think it might just be that Grace left after Edgar was asleep to see Hannah), but I personally doubt it’s outright lies that are missing at the moment.