Yes, Terzic was a key member of Dortmund from 2018 to 2022, successfully leading them to the final, but they never won it. But well, at least he had some good experience in the Bundesliga. He's currently without a club. However, no decision has been made yet.
The following factors are suspected to be the reasons why Leverkusen sacked Ten Hag in just three Bundesliga matches. One of the most serious is the players' lack of understanding, even during training sessions and matches. This is truly devastating.
[..]
When we consider the progress made by Dortmund since Terzic arrived, we find that there has been actual improvement, although it has not yet paid off with major trophies. I believe the interesting part of the storey is how they were able to reach the stage of nearly being champions, so they have some impressive background in their game. As you can see, this type of experience is not something that many young coaches can go through. In the meantime, the case of Leverkusen and Ten Hag reveals just how thin a thread the connexion between the idea of a coach, and the willingness to agree to it by the players, can be. In this light, we can observe that, the problem does not lie exclusively in the results but the absence of team connexion. I believe that this reflects more on the very fast decisions made by the club management.