You are correct, MST and LCK don't go beyond the limits, but the plans are fine.
For Fonewm plan, although Hylian shield is mentionned, all the listed max MST alternatives actually consider using any shield (so not only Hylian shield but also merges, Alis, Vol Opt or whatever)
RR costumes and Hylian shield all give the same ATA and MST amount to the character stats (0 and 20) which is why they are usually listed together for the same max plans, but RR costumes give an additional bonus (all stats but MST and LCK) to your final gear stats. I guess it can be confusing to see them listed together for a same configuration while RR costumes are actually better because of that bonus.