Dealing with feature classes in gdb with domains is less than satisfying at the moment. "export features" keeps the domains and offers in environnments the possibility to "transfer field domain descriptions". Unfortunately latter option does not work for the data I'm working with (https://s.geo.admin.ch/yrr98brihwkd).
As soon as I use a gp tool like "clip" or "dissolve" which creates a new output layer I lose all domains and the result contains only the domain values.
My workaround: python script to add a field with the domain description to the attribute table. but thats cumbersome and takes way too much time for big data.
Thus I suggest that each geoprocessing tool preserves the domains or at least gives (a working!) option to keep domain value, domain description or both in the output data.
