FYI I just managed to buy compensation for a rail segment. 4.78 CHF for 16 points. I can see the points posted in the account already.

It's definitely a bug since their terms say no compensation for ground transportation can be bought. Not sure if they will audit this and retract the points so tread carefully.

(btw I also bought a batch of compensation for other flights and found out the hard way that LO O class shows up as 2x the points it acually grants, so beware)