I'm trying to create a collection with some relative date criteria and it looks like the UI is missing some things that should be there. In particular I am talking about the "Within next/last" and "Before/After relative date" options. I have screen shots from 5.0.5 here https://i.imgur.com/JcZSp0e.png and https://i.imgur.com/OtHWBbR.png
Within Last - I guess this is supposed to be number of days? That seems to work. This page https://docs.plone.org/working-with-content/using-collections/newstyle/creating_collections.html suggests it should say "days" at the end, but it does not.
Before relative date - this looks like something failed to render. No value I enter here seems to work, but I suspect some complex widgets are meant to render.
I also tried Plone 5.1rc1 via https://www.plone-demo.info and it looks like the same behavior there as well.