Yes, all karel progs are specific to a robot version.
I am also using KTrans to compile my .kl files. I've got an robot.ini file which controls the version. I think I generated that file with "setrobot.exe" which if I remember correctly I got from the same WinOLPC folder you've already located.
Below is what I've got in my robot.ini file. "Compiler8dot20" is just the name of a RoboGuide workcell. I am not sure what the individual values do though.
[WinOLPC_Util]
Robot=\C\Users\XXXX\Documents\My Workcells\Compiler8dot20\Robot_1
Version=V8.20-1
Path=C:\Program Files (x86)\FANUC\WinOLPC\Versions\V820-1\bin
Support=C:\Users\XXXX\Documents\My Workcells\Compiler8dot20\Robot_1\support
Output=C:\Users\XXXX\Documents\My Workcells\Compiler8dot20\Robot_1\output