Legacy Value mapping description tables and fields are not picked even though they are defined in System type

We have defined system type for our source system and target system and all lookup tables have their description table and fields available in system type but when we copy the wave to a new wave, they are missing from value mapping source table. I checked with support team and they mentioned that there is no automated way to repopulate it rather then a manual step(work). I can't think that this is real as there would be some event which will trigger this even from either design or Map, which we are missing as a new wave it self trigger to bring those values based on the system type information and data pull for those in their respective database for all DD** tables. Looking for a quick answer on it to get rid of multiple questions from business side. This must be a part of product, which will be update the source & target tables to provide description as business people won't understand the technical values.