Hi @giuliaspiridigl​,

Am I understanding correctly that you're getting unexpected results when exporting KML from 3DCityDB? It might be best to contact 3DCityDB directly as we have limited expertise in that software.

One potential issue from the FME side that I could think of though is to check the CityGML output from IFC. While a generate-workspace translation with no transformers will succeed, it will lump all the common CityGML feature types together as just GenericModel (and I think one other), which could lose out on information on further transformations. We have a few tutorials of different levels of detail in our BIM Tutorial here if anyone is looking for a reference for that. If your workspace doesn't look similar to this example, it might be worth checking your CityGML output in the Data Inspector to make sure there are other more specific feature types than GenericModel.

I'd also be curious what you get if you used FME to convert your CityGML back into KML rather than using 3DCityDB and if there's a difference? Hopefully that helps to narrow down your issue.