Welcome to the forum! 
Not that I know of, no, although ─ and I can only speak for KDE Plasma, because that’s what I’m using ─ the Plasma desktop does allow for (a user-selectable amount of) feedback to be sent back to the KDE developers, albeit that this is switched off by default.
Several individual applications ─ mainly browsers like Firefox and Chromium ─ offer this functionality separately (and in the case of those two, it is enabled by default).
The Manjaro developers mainly rely on user reports from the community as posted here at the forum, as well as upon information available from Arch and from the larger software projects upstream, such as KDE, GNOME, et al.
All software is also thoroughly tested via the Unstable, Testing and Stable Staging branches before being pushed out to the Stable branch.
Every major update to each of the branches is announced on a dedicated thread under the Announcements category here at the forum, where people can also report any difficulties they had because of the pertinent update/upgrade. An example follows below.