With all due respect, Alratan. You are not a senior encouraging a junior or a colleague to develop thier talent. You are the finance background manager telling his technician "Have you tried turning it on and off?"
You have no idea what Johann's skills and expertise is. You have no idea what his plan to develop it is. All you have is an assumption that you know better.
Mathilde is Johann's boss. She is his senior encouraging a junior to develop their skills in a way that she's decided is useful for her enterprise. If she tells him, for example, that he's going on a training course to learn more about diplomacy with dwarves, then it's his job to go on said training course. He can push back and ask her to change her mind if he has good reason to believe he knows what the course would teach, or there's a more valuable use of his time, but that's something he would need to convince her of. The way she told him to get training in punching from a punch cleric last turn is a pretty clear cut demonstration of that. This isn't about encouragement to develop their talents in some abstract sense, it's about having someone being taught job specific skills as one of the parts of their job.
What we know about Johann's skills and expertise is that he uses magic to skip straight to discoveries rather than using mundane intelligence or skill, as that's what his character sheet explicitly tells us. We can only make decisions based on that. We also know that his highest stat is Diplomacy and his second highest stat is Intrigue. That means, for example, that we do have a pretty good idea of Johann's skills and expertise is at a high level, and so, for example, can decide that an approach that leverages what he's good at and minimises what he's bad at, such as maneuvering Gotri to drop some hints based on what Johann has learned magically are likely to be more productive than pushing on the stat that, of the five we know of, he's weakest at, and the description of explicitly criticises his ability:
Johann, Magister of the Gold Order
> Johann's natural glibness sets off every suspicious bone in your body, which is all of them, but you're pretty sure you've got a good read on him.
< Every time he thinks he's got something by you, it's come back to bite him later. He's accepted that it will be easier for him to be your employee than to be your problem.
Armament: Handgun
Speciality: Fisticuffs
Mission: Reverse-engineering Skaven technology
Diplomacy: 19 - Johann is naturally likeable and gets along with most people.
Martial: 15 - There might be a point in the future where you'll regret not stopping this here and now.
Stewardship: 15 - Some might call gilding your body 'ludicrously expensive'. Johann considers it an investment.
Intrigue: 18 - When most of your body is gold, you learn not to draw attention.
Piety: ???
Learning: 14 - Johann leans heavily on magic to skip right to the discoveries.
Magic: 6 - Johann has a natural gift for elemental Chamon.
Disciple of the Pick: Johann has fallen under the tutelage of an order of Priests of Grungni that seek to emulate not the Ancestor-God, but the pick that the Ancestor-God wielded.
Gilded: Johann's skin from the neck down is made of gold, as are some of his internal organs.
Inflexible Magic: While his magic excels at a handful of tasks, some have proven to be completely out of his reach.
Packmaster: Johann is the proud father of five surprisingly friendly and gentle wolf-rats.