What would be the purpose?
- To improve your writing skills in your own language?
- To show people learning your language the right way to write?
I was checking with the filters and I saw that some teachers write in their own language to save the lesson for their students (good idea). But out of that case I with the current notebook filters, I don't think it makes sense to write notebooks in your own language if you are not a teacher trying to explain something.
Have you tried? (I saw some Spanish native speakers writing in their own language and other spanish native speakers making corrections, very funny for me).