Robby, first of all, you have a fine eye! It is ever so slightly a little to the left. However there are a few things going on to make it appear more left of center than it actually is. If measured from the centerline of the outside letters, then it is exactly centered from the left barline to the first of the double barline. But the combination of:
a) the eye taking in the bar as being encapsulated by the single-to-double barline
b) the “v” being wider than the “l”
c) the intrusion into the bar of the Rehearsal Mark
gives it a more slight-to-the-left look to the centering.
Even if Dorico were to have “centered on bar” capability, I doubt that it would give that perfect centered look out of the box as different fonts, kearning, styles, etc. will always have an effect on the visual aspect. Things will need to be manually moved in those instances where optical illusions are happening, and much of this is an artistic, individual’s decision. I hereby plunk down my 2 cents.
[Edit] I just thought of another thing. Placing this text on the 3rd beat is no guarantee that it will be centered because the location of beat 3 it is dependent on the content of the bar, so Daniel’s suggestion might only get you close to centered.