Apparently the only purpose of GetNumJournalQuests is to display that "Quests : num/25"
but the indexes change as soon as you complete a new step of any quest i think (i didn't exactly figured that one), which made this hard to detect. (not to mention that getting no nil error when iterating an empty array is a bit counterintuitive)
I found an even easier way to iterate recently but never used it and i didn't keep the test, maybe something along getnextquest. But anyway, it's just a 25 lines array.