Yes both Lutz and Tuuli operate in very different fields. Lutz works in a rapidly growing new industry. While he may not earn as much as Benno, who is likely now wealthier or at least comparable to an average mednoble in terms of assets, he is still probably earning an executive-level income. After all, he is the first Gutenberg and the most knowledgeable person regarding plant paper production.
Lutz’s mother even noted how difficult it would be to find him a wife who could earn a comparable income within their community, which is why she was very happy when he became engaged to Tuuli.
Tuuli, on the other hand, is a highly skilled craftswoman. She has a noble patron in Rozemyne and is sought after not only by high-ranking nobles but even by royalty. In addition to her salary from the Gilberta Company, she likely earns a significant amount through commissions (Given her status, she can also reasonably charge premium prices if she chooses to). It is said that the more intricate a hair ornament is, the more expensive it becomes, and such pieces are far from cheap. it is hard for normal nobles to buy one, even an archnoble like the Groschels only gifted it in special occassions like when Berthilde she was gifted one by her parents and another by her sister when she started going to the academy. So hair ornaments are probably comparable to something like an expensive smartphone irl.
So at that point, their incomes are probably at least similar… but the real question is, who ends up making more in the long run?