Thanks for reporting this. It looks like this same spelling is present in several areas. Retraction distance, Retraction Vertical Lift, Retraction Speed, Retraction Script, Tool Change Retraction Distance, Tool Change Retraction Speed, Force Retraction On Layer Change, and Minimum Travel Distance for Retraction.
I've reported this for our development team.
"A bird does not sing because it has an answer. It sings because it has a song."