Great job people! I love the Kalam font!
I have been using the font in my journal software for its handwritten look. It works prefect when there are no numbers within the text.
1 and l (small case L)
2 and Z
5 and S (not as bad as the above two)
0 and O (quite obvious)

Wonder if the shapes can be tweaked subtly to make them different enough to not get mixed up easily.