Yes...it's for indetify outern triangle and inner triangle,about -4- on third image,it's a close up and could be not clear which area i'm showing
4-i = 4 inner (interno)
4-e= 4 outern (esterno)

forgive me i did it quickly...i mix Italian and English..some tolerance.. :)

Many times i found same problems when filleting solid fonts,so i decided to show this "shortcut": simplify or use rebuild command to clean points of font splines before extrude.

M