Update: I spoke too soon… 😔 We moved Pekoe and Lottie out to their final living space (living room) and expanded every 24 hours until they had half of our living room. I thought they were doing so well that I gave them the other half of the living room too and that, in combination with a cleaning of their litter box and enclosed area, must have been too much all at once because I woke up one morning to multiple tufts of fur and water splashed around. Thankfully, there were no wounds.

We moved the two back to their neutral bonding space for a day, where they did great: no fights, no chasing, no fur pulling, just a very nervous Lottie around Pekoe, who seemed to be the initiator of the chasing.
At the recommendation of our rescue, the two were moved back to their space in the living room because they did fine in the neutral space and we’ve been keeping an eye on them since. We removed the blankets and hidey boxes, leaving just their carrier and litter box, and a few chews to keep them entertained.
Our issue now is that Lottie is understandably nervous around Pekoe and, while they were able to hang out in the litter box together in the neutral space, she immediately hops out of the litter box in the living room when he enters. We have mutual grooming but Pekoe still occasionally chases Lottie, who runs away. It seems like there’s been a lot of mixed signals from these two where they will groom one another but then Pekoe gets too eager with requesting grooming and that spooks Lottie, who runs and triggers Pekoe to chase her. I understand that Lottie has to build her confidence around Pekoe again after their scuffle and Pekoe needs to learn her boundaries, but is there something I can do to help rebuild the trust between them?