Yes, the GSmini speed increment is added to create a managed speed target on top of the Vapp from MCDU. That is why modifying MCDU is the preferred method over SEL SPD, in cases where the auto-calculated Vapp is not desirable
FD
Amending Vapp in the MCDU is not a preferred method but the only method because GS mini is simply not available in select speed. It will behave like conventional aircraft. In very gusty winds Vapp can be amended up to 15kt.