You need to modify this line:
monster .eventmap$,0,0, "--ja--", .mvpid[.round], 1, strnpcinfo(0)+"::OnMvpDead";
to
monster .eventmap$,0,0, "--ja--", .mvpid[.round], <your qty>, strnpcinfo(0)+"::OnMvpDead";
where <your qty> is the amount of MVP that you want to spawn.
Also change this:
OnMvpDead:
getpartymember .party_id, 1;
getpartymember .party_id, 2;
to
OnMvpDead:
if (mobcount(.eventMap$,strnpcinfo(0)+"::OnMvpDead") > 0) { end; }
getpartymember .party_id, 1;
getpartymember .party_id, 2;
so you only finish the round when all the spawned monsters are dead.