I think CALs have "normal" leakage.
If you use them at home/work almost noone will listed to what you listen, unless they are very close to you. Man... my DT990 are open and don't leak that much.
If you are on a bus, well, unless you use some noise-cancelling stuff, you will do a sound war (your headphones vs outside noise).
I wouldn't worry about leakage with CALs IMHO.
By leakage you are also talking about them leaking in sound too right?
I m not and heavy commuter i take 2 10 minute bus drives
I mostly will use them at bus stops , while walking to class , on school halls.