If I had a recommendation at all, it would be to put the tenderpaws in danger. I think there’s plenty of potential for these young mice to be put in a situation where they’re under threat in a way that will challenge your players. Bear in mind that, by definition, these tenderpaws are looking to enter into the Guard - this means that it’s very likely for them to be eager prove their worth and jump into situations they’re not ready for, and need the players to bail them out of. Have them sneak off to investigate some tracks your patrol came across once the patrol members nod off during camp. Or at minimum, I would have a formidable beast descend on the group while they’re traveling. Now the patrol has the dual focus of both dealing with the creature directly, as well as trying to make sure the tenderpaws are protected during the encounter.
If the violent aspect isn’t what you’re looking for, I would try and shift the focus towards the patrol testing the tenderpaws during their travels as a way to evaluate the young mice. This is a great opportunity to make a lot of use of the Instructor skill, which can be very useful for your players once they finish with this part of your campaign if none of them already have it, or if someone has it and isn’t paying much attention to it. The Instructor skill can really ramp up player advancement by using it to give teammates checks they need to increase skills, so showcasing it here can move your players to looking at it more often during play once they’ve completed the escort mission(s).