Hi @fleischmannHVTJ3. I do not think they have exposed those abilities through Inventor's API yet. We do have access to the related Application.NotebookOptions property, which returns the NotebookOptions object, which appears to provide equivalent control to the 'Notebook' tab of the Application Options dialog. But I could not find true API methods for adding new notes of that type into documents. We can access the 'commands' (ControlDefinitions) which exist behind the manually accessed user interface controls. But attempting to use those would be like trying to 'simulate' manual mouse &/or keyboard user interactions, and not the same as API automation. Executing the command behind the one controls would likely just visibly change the 'Environment' to the Engineer's Notebook one, and initialize the user interface for manual user inputs (editing a note). There would not be any intuitive way to do the required following actions, such as entering text and/or editing the format of the text, and so on.
Below are some of the 'Commands' that I found in a search of all commands, which had the 'Notebook' text in their name. They are just the names of ControlDefinitions, not the names of API methods.
NotebookAlignLeftCmd
NotebookAlignRightCmd
NotebookArrangeNotesPopupCmd
NotebookArrowCmd
NotebookArrowReverseCtxCmd
NotebookBoldCmd
NotebookBulletsCmd
NotebookCenterCmd
NotebookCreateNoteCtxCmd
NotebookCustomizeCmd
NotebookDefineNewNoteFolderCtxCmd
NotebookDisplayNoteCtxCmd
NotebookFinishNotebookCmd
NotebookFontCmd
NotebookFontSizeCmd
NotebookInsertCommentCmd
NotebookInsertFolderCmd
NotebookInsertNewObjectCmd
NotebookInsertViewCmd
NotebookItalicCmd
NotebookNextNoteCmd
NotebookPreviousNoteCmd
NotebookRestoreCamerasCmd
NotebookShowInstanceNotesCtxCmd
NotebookTextColorCmdImage
NotebookUnderlineCmd
NotebookViewFreezeCmd
Wesley Crihfield

(Not an Autodesk Employee)