First of all, thank you for the donations! I am astonished by the contribution rate, I have not expected to find this quickly so many people willing to help develop KiCad!
We did our best to make it clear, but I will say it explicitly here: the donations are used to boost the development process, meaning shorten the time to reach v6. We plan to do so by outsourcing work whenever possible. It is not a kind of budget that would allow us to hire a team, but surely we can buy a few features. We would have never dared to promise that we will deliver v6 in 600 hours, both you and us realize how much effort it takes to release a new version. I swear I was getting even more impatient with v5 release than many users did.
Rene is right regarding 5.1 - we need to focus on wxGTK3 fixes now. This is one of unexpected obstacles that we need to deal with. It means that we want to release 5.1 soon, but it will not receive new features, just some minor improvements, mostly related to the user interface. The main goal is restore the user experience on modern Linux distributions.