ZRH is extremely efficient for connecting; even with 25 minutes I think it would be possible at a brisk walk. I had to do the reverse and rush from T2 check-in to T1Z a couple years ago when I got rebooked on short notice, and it was ~45 minutes at a full sprint when not queueing for security or passport control. That doesn't include time from the check-in hall to the plane at T2, which is even longer.

That said, I'm not exactly sure what the timing is on the flights, but there is a second service to HKG on LX later in the day your friend could be rebooked on if the inbound from TXL is delayed, or even a nonstop on Korean to ICN that could work. Seeing as there are options that would get them there the same day in case of problems, I would opt for ZRH.