I read from the credits REBOL from Carl Sassenrath is used. Is it that the case?
In the original (PC/MAC/Linux) release of Machinarium, yes. We talked about it back when the game was originally released:
here But I, personally, haven't seen the iPAD2 port credits. Is REBOL still mentioned in the iPAD credits?
Also, if you're into REBOL, you'll want to check this out, The guy that recently
interviewed JD wrote: "I will be releasing an article about the making/porting of Machinarium for tablets soon covering all the technical details", so there may be more REBOL details coming there.