@Salah Hello Salah,
Per my research, the ilearn interface is supported on Azure Machine Learning Studio(class), but I can not find any official document indicate this is supported on Azure Machine Learning Designer as well. Sorry for the experience. https://learn.microsoft.com/en-us/azure/machine-learning/studio-module-reference/ilearner-interface
If there is any document you are using has any clue please let me know.
Regards,
Yutong