Solved!
Go to the GRF with your translations and go to that path:
[GRF]/data/luafiles514/lua files/skillinfoz/SkillTreeView.lub
Find something like this:
JobSkillTab.ChangeSkillTabName(JOBID.JT_NOVICE, "1st", "2nd", "3rd")
JobSkillTab.ChangeSkillTabName(JOBID.JT_NINJA, "1st", "2nd", "3rd")
JobSkillTab.ChangeSkillTabName(JOBID.JT_GUNSLINGER, "1st", "2nd", "3rd")
JobSkillTab.ChangeSkillTabName(JOBID.JT_SUPERNOVICE, "1st", "2nd", "3rd")
JobSkillTab.ChangeSkillTabName(JOBID.JT_TAEKWON, "1st", "2nd", "3rd")
JobSkillTab.ChangeSkillTabName(JOBID.JT_STAR, "1st", "2nd", "3rd")
JobSkillTab.ChangeSkillTabName(JOBID.JT_LINKER, "1st", "2nd", "3rd")
JobSkillTab.ChangeSkillTabName(JOBID.JT_STAR2, "1st", "2nd", "3rd")
JobSkillTab.ChangeSkillTabName(JOBID.JT_DO_SUMMONER, "Summoner")
JobSkillTab.ChangeSkillTabName(JOBID.JT_DO_SUMMONER_B, "Summoner")
Rewrite the string as you want.