Imperial mandate questions

I’m a bit confused on what counts as an immobilize effect. I get what CC is accounted for but some specifics confuse me.
Like ornns brittle causes airborne and is tied to his W, would it have reduced cd?
Karma and heimendinger ults impower abilities with immobilizes are they reduced? Only when empowering certain abilities?
How about urgots ult? If it never suppresses (re casted) does count? If it’s auto reeled in (only one activation) is it still applied?
Is trundle pillar and anivia wall included due to airborne? Is it only if it applies the cc or if it is capable of cc’ing?