The font lil.font has bugged characters from 16 to 26. All of the pixels that should be there are indeed present in the userdata; however, their width adjustment nibbles are not set and so they appear cut off:

print(chr(26)) --Yen symbol is cut
poke(0x4008, 34, 34, 34, 34, 34, 3) --fix nibbles
print(chr(26)) --Yen symbol is whole again!

To make it simpler you can do this:

poke(0x400d,3)

Also, if you're using lil-mono.font, you'll need to run the following additionally.

poke(0x4005, 3)