Not sure why this is possible, but in the FGDB Writer it is possible to create a coded domain into unlimited coded domain.

No idea what is the point of being able to do this, because in ArcGIS this is not supported at all. Well, maybe there is something new I missed from ESRI. But yet I can’t see in ArcGIS Pro the SECOND_CD I created.
Anyone could tell me what is the purpose of doing this ? What am I missing?
I’m on FME 2024.1.
Thanks!