It's not very nice to call teachers by the first name.
It's not very nice to be calling teachers by the first name.
What's the difference between them? The second one is grammatical? (The versions with the dummy 'it' removed are below.)
To call teachers by the first name is not very nice.
To be calling teachers by the first name is not very nice.
I feel the "To be calling here" is awkward because we can write "Calling teachers by the first name is not very nice."