Great job documenting that process @AlexKorzun .
I just wanted to add one more little thing in there. Since @rjkdk mentioned wanting to put this note in the 'margin' of the drawing, I would alternatively suggest editing the 'Border' (instead of the 'Title Block') and inserting that text block there, maybe just barely outside the lines, if there is room for it.
This could either be set-up once manually within each of the drawing template documents, or could be done completely by code, if needing to apply it for older drawing documents. If done by code, the code could either find and edit the sheet's existing border sketch, or just have the note be independent of the border or title block, and simply overlay them at a certain predefined position, where it isn't covering anything important.
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Wesley Crihfield

(Not an Autodesk Employee)