Fluid problem solved
Added 2024-12-27 23:08:41 +0000 UTCI encountered some issues with FLIP fluids in the scene I shared earlier, but I believe I've pinpointed the problem. The fluid was passing through the chair because there weren't enough fluid calculations per substep.
The workaround will make rendering take longer, but after spending so many hours on this, I'm glad I figured it out. I wanted to share this since I've been quiet for a few days; these kinds of problems can be frustrating, but we manage to get through them.