Thank you. Unfortunately, this seems highly unfinished:

1. Even though https://www.easyreading.eu configuration lists English, the (Firefox) extension (mouseover/ tooltips for the buttons on the right) are in German only.

2. Many standard/common websites (like GitHub project home pages) seem unsupported. The buttons on the right don't show up.

3. The ruler is unfinished, or impossible to use.

4. The initialisation/installation of the (Firefox) add-on is SLOW. If you have 1000 (a thousand) tabs open (in current Firefox 114.0.1), it takes over a minute: It freezes whole computer!

5. Since this was EU/publicly founded, and the initial developers are from a university, why don't you put the project on GitHub, or some other open source repository. People could report issues, provide screenshots, suggest and contribute fixes.