trying to get the ultimate lepic code but realized it drops from events

[ELPANDA2003]

why is this a thing why cant i just farm for the code like with the other bosses were i go into the mission for example slumber valley i can choice to get the relic with Lepic or Gley and by completing that mission i have a chance to get the relic i want or that little weird vile. Like farming an event that has a 25 percent chance to drop this relic is ridiculous imo cause half the time you never get the thing