As an option you could purchase Artist as an upgrade for only $50. If you feel it's wrong to install your copy of Platinum on a second machine this would be a solid solution.
But you would want to have it confirmed that the offset feature is available in that version which I'm 99% certain it would be.
I checked my version of Sonar X1 LE and it has the same features. At first I didn't see the offset option until I realized you have to check "advanced" to see that tab.
Double check MC7 that you had not missed that too.
I guess X3 LE ? is what comes free with Tascam interfaces and possibly other Tascam hardware these days. My Sonar X1LE came with a Roland keyboard. I'm not sure Roland will continue shipping with a version of Sonar.
I used the free copy to upgrade to X3 Studio for only $99. Freebies are worth more than the face value for sure.