A 4-day pass works fine for that.
I never use that "plan your tour” tool. I do the planning myself :)
HOla!
THE glitch MAY be Mad-Brdx: NO direct trenes, need to use Euskotren for some part Donostia-Frontera-pay a few€ and it may mean this causes that glitch= count as 2 where as with speed and early dep. could do in 1.
Also: its for march probably now still too early, but I i highly doubt if a pass is worth it for this (I guess you fly back on Vueling/other? Check fixed booked advance prices. Also-if money is an object-consider BUS-FLix or BlaBla, slower but much cheaper.
IF choose pass-or maybe have bought it with discount (there will be new discount period between Xmas-Nw Yr): AVOID that expensive Thalys Par-Bru and Bru-Ams. The latter has hourly free local trains, Par-Bru can now do without any RES but much slower in trenes regionales via Maubeuge-Charleroi-or TGV only for LIlle,then local BE trenes.
OR make a detour in 1 day TGV till LUxembourg=you collect another country for free! then hourly local tren to Bru.