I couldnt see them in the tab but they appeared for me.
Its possible. I dont have the DLC but 100%.
I did this to get all notes
First I used GiveExplorerNotes 688 - 690 to get the HLNA notes. After each command I closed the panel because only the first note is shown.
Then I started from 1 until the troohy poped . After 20 commands I closed the panel again. It seems like you won't get the following if you put them all in a row.
Be sure to make some cloud saves in the process. The game still froze sometimes.