Are there any usability tests regarding LibreOffice?

If yes, is there an online source to see the results?

Something like Canonicals usability tests webpage would be nice.

No, there are no usability tests performed by the LibreOffice project / TDF.

It is very hard to not create a biased test anyway - whatever is your desired result, you just design your tasks that way/pick the testing audience accordingly. Especially with a software that is used for so various different task, that differ so much in complexity, and where users’s demography and background is so different, it is nearly impossible to design a useful/fair test that stands critic questions regarding the methodology.

So bottom line: We have an ux-team that does its bests with the currently limited capabilities there are regarding changing/adapting the UI. (currently LO’s UI-layer is not very flexible, but as touch-control interfaces will have to bee added, this layer very likely be revamped as well, making it easier to make larger changes).–-summary/