Hi Marco,
Thank you for the details, I have found the issue.
The search logic was set to ‘OR’, which is a pretty loose word logic, and the relevance of different results, matching either of the words was higher. I have changed it like this: https://i.imgur.com/LNC2OoW.png
Now, the results should be much more relevant and strict to the term, and better calculated by relevance and occurence.