Depends on the size of the Cordyline - if its a 20 foot giant, it'll have a fair amount of root, if its only about 5 feet, not a huge amount. Even at 20 feet, they don't have extensive roots like broadleaf trees do.

Also, once formed, the roots don't expand in thickness, like broadleaf or conifer trees do. Any damage that is done is from the wall actually touching the expanding trunk base and new roots of the Cordyline, not a root from one 5 meters away.