You can create a note for a specific target by the following (replace "Circle" with icon name of your choice when you create the macro... but there are only a few characters left within the macro limit and I had to condense parts of this to get it to fit)
/script p="player"; x,y=GetPlayerMapPosition(p); t=UnitName("target"); icon="Circle"; /script Cartographer_Notes:SetNote(GetRealZoneText(),x,y,icon,(UnitName(p)), 'manual',true, 'title',t) /script DEFAULT_CHAT_FRAME:AddMessage(format("Added %s",t))
If you want that to also open the note for editing, add the following to the macro... alas, you can't do this because of the character limit of macros.
/script Cartographer:OpenAlternateMap(); /script Cartographer_Notes:ShowEditDialog(GetRealZoneText(), px, py)
This explains how to use the import function. I'm not going to guarantee that this is still the correct method, but probably worth a try (backup your data first).