1. Calling PRIM_TYPE resets and locks PRIM_FLEXIBLE, even for non-type change parameters. Meaning, you change a simple thing like hollow, and it turns off flexi, and takes a completely seperate call to turn it back on. Calling flexible will fail in any parameter set that also calls type. So to change the hollow on a box that has flexi turned on, it takes two calls, one to change the hollow, and one to reset the flexi.

2. Working with individual sides with PRIM_COLOR and PRIM_TEXTURE is broken. These two constants can't be used in the same call when dealing with individual sides, as the first set called will set the entire prim to the last entry once the second set gets called. example:

This works: (sets the color to green for all sides but side number 1, and sets side number 1 to black, then changes texture to blank)
llSetPrimitiveParams([PRIM_COLOR, ALL_SIDES, <0, 1, 0>, 1,PRIM_COLOR, 0, <0, 0, 0>, 1]);
llSetPrimitiveParams([PRIM_TEXTURE, ALL_SIDES, "5748decc-f629-461c-9a36-a35a221fe21f", <1, 1,0>, <0, 0, 0>, 0]);
This does not:
llSetPrimitiveParams([PRIM_COLOR, ALL_SIDES, <0, 1, 0>, 1,PRIM_COLOR, 0, <0, 0, 0>, 1,PRIM_TEXTURE, ALL_SIDES, "5748decc-f629-461c-9a36-a35a221fe21f", <1, 1,0>, <0, 0, 0>, 0]);