“Diligent" is not a common word in this context. A more common translation of "rajin" would be "hardworking". Reported.

This sentence assumes that tono is a boy .. nowhere does it actually state that tono is a boy .. surely it should state ..tono bukan laki laki yang rajin ..to actually be correct .. remember this is a basic programme directed at native english speaker who would not necessarily know if tono is a boys name or a girls