Hello Riccardo,
In Kyma 7, there are new Sound classes that did not exist in Kyma X, and there are improvements and additions to Sound classes in Kyma 7 that Kyma X doesn’t know about. We are able to move Sounds forward in time to the newer version through automatic translations, but there is no way to go backwards in time (because, 10 years ago, we didn’t know what was going to be in the new Kyma 7 😉 Unfortunately, your strategy of hand copying is really the only solution. Or you could try restricting yourself to using only the subset of Sounds that are in the older version.