Your question has received upvotes, which generally means that some people find it interesting. For this question, the reason could be simple: Maybe there aren't enough people competent in Scala on CodeReview.SE.
Still, I'm sure we can find a few points to improve in your question.
1. You don't actually ask any questions. You write:
Is it well readable or should it be formulated differently.
Put a question mark at the end to indicate it is indeed a question. Personally, I prefer to explain/comment on the code at the beginning, and then ask the questions I have at the bottom. That way they stand out, and whoever is answering will have to scroll less to see them. In either case, be clear about what you want and expect from the review. If you have anything to remark yourself, then you should generally fix that and edit the post to reflect the revised code. Try to improve your own code as much as you can before posting.
2. Remove all non-relevant code. In your question, I would have left the unit tests out (but offered to show them on request). Consider putting in a tiny
main (or whatever it is called in Scala) to make the snippet runnable.
Finally, it is possible that the code looks reasonably OK and that simply no one have taken the time to point that out in a comment, again perhaps because of a lack of Scala competence.
To raise attention around a question, you can also try starting a bounty.