I'm betting the one student Raim couldn't charm was Callego.
P.s. Although Balam stated he was classmates with Callego and this chapter established that Balam won that year so Raim's claim she didn't win because she just couldn't charm the winner wouldn't work out.
i wonder how they'll get points, though? If the others were in the same part of the forest as Iruma and Lied, the possibility of someone giving up their points would've been high but then again, that would be boring. So how?