The journey itself could be full of danger. There could be bandits or rogue ninja along the way who target Naruto because of his fame. Also, the terrain between Konoha and Kumo might be difficult to traverse, with mountains, rivers, and forests full of wild animals.
Well, in Kumo, Naruto might face challenges related to power struggles. There could be certain groups or individuals in Kumo who see Naruto as a threat to their own influence. He's a powerful ninja from Konoha, and some in Kumo might not want him to gain too much power or popularity there. Another biggie is making new friends. It's not easy to break into an established social circle in a new village, and Naruto might find it hard to find people he can really trust and rely on.
He might face new and powerful enemies. In fanfiction, there could be hidden threats in the outside world that are different from those in the village. These enemies could have unique abilities that Naruto has never encountered before, testing his combat skills and strategic thinking.
Well, in some fanfictions, Naruto leaving Konoha for training means he has to face new enemies outside the village. These enemies might be more powerful or have different fighting styles that he's not used to. Also, he has to manage his resources on his own. Without the support of Konoha, getting food, water, and training equipment becomes a problem.
Adapting to a new ninja system could be a big challenge. Kumo may have different training methods, rules, and traditions compared to his home village. Naruto would need to learn and adjust quickly if he wants to survive there.
One challenge could be loneliness. Without other males around, he might struggle to find that sense of brotherhood or male camaraderie. He may feel isolated in some ways.
One challenge could be Naruto's stubbornness. Naruto has his own ideas and ways of doing things, and getting him to listen and follow Kakashi's guidance might be tough. Another is dealing with Naruto's past traumas. Kakashi would need to help Naruto overcome his feelings of loneliness and being an outcast. Also, Kakashi has his own responsibilities and missions, so finding time to be a proper adoptive father could be a struggle.
He might meet a young and idealistic ninja in Kumo. This ninja could show Naruto a different way of looking at the ninja world. Maybe this Kumo ninja has a more peaceful approach to resolving conflicts, which makes Naruto re - evaluate his own views on fighting and rivalry between villages.
One possible reason could be a mission. Maybe the Hidden Cloud Village (Kumo) requests Naruto's help specifically for a very important and dangerous mission that can only be accomplished by him. So, he has to leave Konoha for Kumo.
One challenge could be time management. Naruto is always so busy with his ninja duties, protecting the village and going on missions. Finding the time to sit down and write would be tough. Also, he might struggle with grammar and spelling since his ninja training didn't really focus on that.
One challenge could be gaining the trust of the Root members. Since Root has a history of being a secretive and somewhat feared organization, the members might be skeptical of Naruto's leadership. They're used to a more authoritarian style, and Naruto's more open and friendly approach could be met with resistance.