Hi Andreas,
Thank you for taking your time and leaving us a note, we highly appreciate your feedback.
We apologize that the app did not meet your expectations in terms of performance and functionality. We will take note of the specific issues you mentioned, such as the lack of ability to limit the number of displayed rows and the lack of diagram rendering, and will work to address them in future updates. We understand that the ability to edit attached Excel files is important and we will work with Atlassian to find a solution for this. We appreciate your input and will continue to strive to improve our app.
Hope that you will give us another chance to change your opinion of our App!
Kind Regards,
Alex Dolara from Excel for Confluence team