This project is an Atom package.
The desired behaviour is to have
Ctrl-Alt-Up on Mac) scroll the page a single line up, leaving the cursor in place.
The same should happen for
Ctrl-Alt-Up on Mac) but in the opposite direction.
You can also use
Ctrl-Alt-Shift-Up/Down on Mac) to move 10 lines at a time (amount of lines configurable).
When the cursor reaches the end of the page, it should scroll a single line as well to prevent it moving off the page (this can be disabled in settings).
Also have a look at line-jumper which allows you to move the cursor 10 lines at a time.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.