MotoSPEC v5.6.1 added a setting that will indicate the forward reference for the swingarm length.
Swingarm length is typically measured from the swingarm pivot axis to the rear axle. On most motorcycles, the swingarm pivot is visible and accessible.
For Ducati Panigale V2 and V4 models with adjustable swingarm pivots, the eccentric adjustment occurs inboard of the swingarm bracket - so the swingarm pivot axis is not directly accessible for measurement.
The calculations for swingarm and chassis geometry now consider the offset between the frame center and the actual swingarm pivot.