@kris there was an issue in the version 1.1.4 with the Mac App Store version of Bookends: it won't be detected unless also the non-Mac App Store version of Bookends is on your system. This is fixed for the second 1.2.0 beta version. Sorry for the inconvenience! As a workaround to get this to work with the 1.1.4 version of Manuscripts, you can simply download the non-Mac App Store version of Bookends from http://sonnysoftware.com, I believe.
@Adam-Buckley thanks, crash reports regarding adding more than one author noted and will be fixed in the next beta.
Regarding author list storing, we allow copying & pasting or dragging & dropping them between manuscripts. We haven't really introduced any kind of an account system (at least yet), that's why storing that information is not stored persistently as we haven't wanted it to become information that becomes locked on the one computer where you made edits where you may want the same info on other computers too.
@Matthias-Beck: right, this sounds exactly it. The issue is that we have built the copy of Manuscripts you used as 1.2 beta in Sierra, and I worked around a certain new Sierra change that would induce the opposite of that effect in Sierra (the whole view would look as it's in lower light) but the nature of the workaround is such that the compensating tweak needs to be done for older systems now…