Hi,
None of these sound to me like natural English.
A."English isn't easy to learn by foreigners"
B."English isn't easy to be learned by foreigners"
English isn't easy for foreigners to learn.
It's not easy for foreigners to learn English.
A."That crate is heavy to lift by them"
B."That crate is heavy to be lifted by them"
That crate is heavy for them to lift.
Which sentences are correct?
Best wishes, Clive