We get some information about the fourth-year students in Book 5, where Crewel explains:
“At Night Raven, students spend their senior year at internships and research placements related to their magical professions.”
Both Crewel and Riddle mention the fourth-year students being on-campus for the culture fair, but we never meet anyone in-game.
Both Ace and Grim comment on never seeing them at the school, and Trey explains that “The typical M.O. for four-year magical academies is that seniors go off-campus for hands-on learning.”
Riddle provides more detail:
“Some people apply to shadow a certain special team in an administrative organization, while others leave to excavate or explore ruins, or to decipher ancient texts. Still others accept internships with magic related businesses.”
We learn a bit more in Book 7, and the orientation for off-campus internships is what begins Book 7.
Crowley explains:
“The internship program is 100 percent mandatory…Each stint is three months, or one quarter. You can choose up to three internships over the course of the year. It’s perfectly valid to devote all three quarters to a single, in-depth internship, as is choosing a different internship each quarter to gain a wider breadth of experience. The internships are at businesses, research institutes, and foundations that cooperate with our school…Be aware that your options will differ based on your electives, class credits, and grades. And in addition to interviews, some internships have special exams you must pass to be eligible. Each quarter, you must receive an evaluation of a B or higher at your internship and submit a report. You will not get credit without those two things. If you receive credit for two of the three quarters, then you’ll qualify to take the graduation exam.”
Concerning spelldrive: While both game- and novel-Leona say that he intends to participate in the spelldrive tournament the following year, novel-Jack points out that he isn’t going to be on campus to do so:
“Both Malleus-senpai and Leona-senpai are gonna move up next year, so they won’t be here for the tournament anyway. We’re lucky we only had to compete with that monster athlete for one year.’
-Twisted Wonderland the second novel (fan translation)
So it seems that presentations at the cultural festival are tied into the internships themselves, so they are allowed (and maybe mandatory?) but spelldrive tournaments are not? Perhaps?
Twisted Wonderland Reference Note 