Getting Pitch/Yaw/Roll of a collided triangle

Use a pivot and align it to the collision normals, then get the pitch, roll , yaw from this pivot :

global PIVOT = createpivot()

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Nx# = 0
Ny# = 0
Nz# = 0
for c = 1 to countcollisions( Entity )
   Nx = Nx + collisionnx( Entity , c )
   Ny = Ny + collisionny( Entity, c )
   Nz = Nz + collisionnz( Entity, c )
next
aligntovector PIVOT, Nx, Ny, Nz, 2, 1

Pitch# = entitypitch( PIVOT )
Yaw# = entityyaw( PIVOT )
Roll# = entityroll( PIVOT )