if you mean that new codes have to be used exclusively with VAMOS-II+TscSet2, then I agree with you.
The new codes seem to me the only info, that BTS can check to know about the presence of the shift (at least if no other proprietary infos are added in Abis RSL).
But from mobile point of view for the application of the shift seems to enough VAMOS-II+TscSet2 (see 45.002).
In any spec they refer to the new codes for the application of the shift.
So everything works. But they did this stuff very complicated without reason.