Hey Swick,
absolutely correct. They did not repeat it on the Elite version of Journeyman page, but it’s mentioned in the Standard version of Journeyman page:
With a cutting area of 48" x 32" you have the ability to machine full sheets of Plywood, MDF, etc… Rigidity is not an issue with 50mm Linear hollow shafts standard on the X Axis (Stiffy is unnecessary)
[…]
X-rail is composed of 50mm Hollow Linear Motion Shafts and the Y-rails are composed of two 35mm Hollow Linear Motion Shafts.
See also
Journeyman Inner and outer width
What they meant is, in fact, not “X-50 on Y”, but Y-50 rails (requested here)