I use a lot of transformations and my question is now if it is possible to use subfoldern in the transformation folder to structure the transformation files?
Based on this another question comes to my mind: Are there any plans to bring transformations to the main UI?
The answer to your first question is no, subfolders are not supported as fas as I’m aware.
The answer to your second is I’m not aware of any discussions specifically about transformations in particular, but I do know the goal is to support being able to do everything in the UI. It will be a very long time before that can happen though as it requires lots of additions and changes in both the core and webuis.