Question

when the narrator asks the boys about their plans, they are evasive.why don't they disclose their problems?

Answer 1

because Nicola and Jacopo already had a lot of hardships in their life and they don't want anyone else to get disturbed by helping them with their problems . Moreover they don't want anyone to feel pity on them because they were very determined and want to do their work by their own hard work and don't want to depend on others that's why they don't want to disclose their problems

Answer 2

when the narrator asks the boys about their plans, they are evasive.they don't disclose their problems because they don't want to share their personal problems with anyone and they do not need anyone's help because they know that if they tell their problems to narrator so narrator will surely help them but they do not need anyone's help and they were not complaining the dynasty and they want to solve their problems on their own.
hope it helps!!