Please make sure to call your submoudles in the root module, and save your template.
Then you should be able to select subentity1 fields from subentity 2 without fully-qualifying them.
In my example I selected Attribute Name (which is on the subentity 1 (attributes)) from attribute-values submodule (subentity 2), see screenshot.
thanks for the response.
The submodules call was made correctly, but we understood (also with Informatica support Help) that to make what we need a costom development was needed.
This because the behaviour that we wanted was a special behaviour avalibale only for certain subentities (ArticleNutrient for example) and to have it in other entities we had to make this custom development.
Thanks again for the answer.