That's true, but if there's even a slight difference, it could cause the keys not to fit properly.
Assuming that they are completely compatible though, your options are -
A) Buying a set of Filco keycaps from EliteKeyboards.com
B) Buying a cheap Cherry G80/G81 or another fake Cherry keyboard from eBay, and cannibalizing it for keycaps.
Cherry doesn't sell keycaps by themselves unfortunately. You also have the problem that you have a backwards-L return which aren't particularly common on Cherry keyboards. I'd recommend perfecting your technique on individual letter keys before moving to things like return or the space bar.