When the number of digits is the maximum, you can create all glyph shapes. You can try any glyph you like!
Also, regarding the UI idea, your 'undo' will be difficult to implement due to the specs of this game script. And, it is possible to jump the cursor to the current character, but I forgot the source code :p so I hope to be able to use it in the next game or later. Thanks for the feedback.