Lini cheat does work but mine was at lv.32. The reason this is because of your clan level.
If your clan level is at lv.9 then lini would be at lv.9.
To beat the game
all you have to do is take the missions were you cannot cancel the mission.
secret characters
Cid-clear all 300 missions
Shara-clear a maiden cry mission then enter any town
ezel- choose gossip in the card shop and then clear the reconciliation mission.
Babus- clear left behing mission and enter a town and clear the with babus mission.
ritz- clear mortal snow mission
semi secret characters-
lini-then complete a mission with the hero gaol as a mission item
Quin- complete missing professor mission.