All good so far. Let's get ability scores hammered down so we can Homebrew it.
We know Int is Low (5-7), and this "The yau-mor follow orders well, but are easily distracted and tricked" seems to imply low Wis as well.
Other similar-HD outsiders:
Babau (M): Str 21, Dex 12, Con 20, Int 14, Wis 13, Cha 16
Canoloth (M): Str 19, Dex 10, Con 19, Int 5, Wis 17, Cha 12
Gulthir (L): Str 19, Dex 14, Con 19, Int 8, Wis 15, Cha 18
Kyton (M): Str 15, Dex 15, Con 15, Int 6, Wis 10, Cha 12
Barbazue (M): Str 15, Dex 15, Con 17, Int 6, Wis 10, Cha 10
Hellcat (L): Str 23, Dex 21, Con 17, Int 10, Wis 14, Cha 10
Blue Slaad (L): Str 23, Dex 15, Con 19, Int 6, Wis 6, Cha 10
Maybe Str 23, Dex 15, Con 21, Int 6, Wis 6, Cha 10?