@viktor(View Post) ok, i'll look at it now, but future glitches with my mod can go in it's thread.
Edit: well, I already have a reason. Each moving solid has a center, and all the solid's particle's positions are based on the center one. The velocity the solid gets when it bounces off something is also based off of that, things farther away from the center add more velocity when it hits something. For a triangle, much more of the shape is below the center. More collisions are occurring from there, and that means it goes upwards faster. I could try making the center closer to the actual triangle's center, that would be the only way to fix it. I might wait until tpt++ though, moving solids have always been glitchy.