When exporting content from an included content from another translated space(with a include library), only the default language of the included content is exported.
Steps to reproduce:
Create two translated spaces (spaces A and B) with two languages (space A: Dutch (Belgium) and French (Belgium)- space B: Dutch (Belgium) and French).
Set up an include library and map languages.
Create page A in space A and translate it.
Create page B in space B and translate it.
Add an include plus macro to page A and reference page B.
Export page A in translation French (Belgium).
The included content in translation French is exported.
The included content in Dutch (Belgium) is exported.