Hello @tomvanroosmalengamil-com,
First of all, we would like to apologize for all trouble you are having.
And actually, the thing is we have not tested Yummy Pro theme with the qtranslate x plugin or any third party plugin besides the one that is recommended by the theme itself.
So as much as we would love to help you on this we are unable to do so as it requires lots of time since we need to do the compatibility testing with the theme. it also falls beyond the support we offer for our product as it is related to third-party plugin.
Hope you understand.
Thank you 🙂 .
Best regards!!