Does this include the following?
- Reading some words/digits in the online computer.
- Walking to the airgapped one.
- Manually typing the memorized words/digits on the keyboard.
Yes, even those methods are not safe strictly speaking. Theoretically a virus can trick you into recording the wrong data. A truly safe cold storage device can only ever safely transmit data out of itself, never receive input data, as such input data can never truly be guaranteed to be secure.
This would make it impossible to even create cold storage in the first place.