I need your help: if an application form for a license is defined as "deficient and illegible", what do you understand?
Deficient: inadequate, lacking, incomplete? Illegible: that cannot be read/understood?
(not a professional teacher). I think you've understood it well, especially the "deficient" comment. "Illegible" does mean "cannot be read". It refers to the writing, that it is literally unreadable. I would say "cannot be read" rather than "cannot be understood" because if I typed "trentatre trentini" that phrase is entirely legible, but it cannot be understood if the reader knows no Italian. If I personally wrote "trentatre trentini", then even someone who did read Italian would find it illegible as I have very bad handwriting.