Add sample text into Space Center. Run this script. Any glyphs that don't exist in the font will be highlighted red. Draw them!

markUndrawnGlyphsFromSCRed.py

# menuTitle : Mark Undrawn Glyphs from SC Red

from mojo.UI import CurrentSpaceCenter
from glyphNameFormatter.tools import charToUnicode

f, csc = CurrentFont(), CurrentSpaceCenter()
text = csc.getRaw()
color = (1, 0, 0, 1) #red

for letter in text:
    g_name = f.getCharacterMapping()[charToUnicode(letter)][0]
    
    if g_name not in f:
        f[g_name].markColor = color        
    elif f[g_name].contours == ():
        if not "space" in g_name:
            f[g_name].markColor = color