Hi,
As of the latest experimentals (from the past week or so), I have not been able to add custom marks to my map. If I place a custom note on the map, it does not show up, but the game still seems to know it is there because it will ask me if I want to delete that placed note if I place the cursor over that square, and then press Ctrl+d (at least I think that’s the ‘delete note’ key combination). No matter what mark/colour combination I use, nothing seems to show on the map itself.
Also, on an unrelated note, I think that Flaming Eyes need to be seriously nerfed (again). They are WAY too numerouse on the map right now, and I have lost several early characters who get blinded, even though the Flaming Eye is not even close to where my character is standing…