I would guess that 7-15 is type IV ?
In C&M, Pale I demons are listed as level 1A, Pale II as level 4H, Pale III as level 8H, Pale IV as level 13H, Pale V as level 18H, and Pale VI as level 27F (and Beyond the Pale as level 50G). Which would give a range of :
Pale I : level 0-2
Pale II : level 2-6 (adjust to 3-5 or 3-6 ?)
Pale III : level 6-10 (adjust to 7-10 ?)
Pale IV : level 11-15
Pale V : level 16-20
Pale VI : level 21-33
Beyond : level 40-60
Using only the 1-100 range of the level chart in section 2.1
There is a slight overlap between Pale I and II and between Pale II and III (thus my suggested adjustments), but overall, I think it fits (and I wonder why the ChCo did not use the C&M scale).