In Blender and maybe other programs the face order of meshes is set alphabetically.
To get faces with llDetectedTouchFace() in scripts in the order you want, name your materials and maybe even textures alphabetically such as :
DO NOT use numbers for the material names to set the order as blender seems to strip them off in the collada file and your faces will be out of order using the first letter of the material name.
While having the order exact is not super critical for scripts or scripting, it can lower the amount of mental gymnastics you have to do when things are in the expected order.