Two-dimensional offsets (X and Y coordinates) are stored as pairs. The car of the offset is the X coordinate, and the cdr is the Y coordinate.

\override TextScript.extra-offset = #'(1 . 2)

This assigns the pair (1 . 2) to the extra-offset property of the TextScript object. These numbers are measured in staff-spaces, so this command moves the object 1 staff space to the right, and 2 spaces up.

Procedures for working with offsets are found in scm/lily-library.scm.

Extending LilyPond v2.25.15 (development-branch).