How to run FMETransformer in pythoncaller

It doesn’t sound like something you wouldn’t be able to accomplish with regular transformers to be honest. If you want to pursue that option, could you please share how you’ve set things up?

I don't understand your complete goal. And that's why I don't know how to come with the right solution.

But if you store the complete geometry, a label “A” and an ID to the AreaOnAreaOverlaying features you can check what portion of A is overlaying what portion of B. And restore the ID and even the Geometry of FeatureSet A.

As the others have said, it is very unclear what you are trying to achieve. In part that is because the phrase “doesn’t work” is not very helpful: do you get error messages? Does it not do what you expect? Does it return strange results? A bit more explanation of “doesn’t work” would already be quite helpful in this case. Personally I find the AreaOnAreaOverlayer not very useful as it is right now, and never use it.

However: Maybe the Clipper would work in your scenario? If you’re worried about the original geometry, it’s easy enough to use the GeometryExtractor to preserve the geometry, and possibly restore it after you’ve done your work.