The Vassal's "Player Aids" does not indicate that these units can perform the "retire and reform" maneuver. The mistake is in the Vassal, right?
More likely an absence on the Player card, but the general rule for all cavalry is that they can retire and reform. The note on the Player aid is more a memory aid than a rule (or in this case, an absence of a memory aid).
I believe Prussian MLNCR cavalry can Retire and reform the same as Russians MLNCR are explicitly allowed to do so on the Player card, and aas all cavalry are allowed to do under the rules.
