Gnome-3-34 extension warnings

snapcraft
1

Hi,
when starting my still-in-development-but almost releasable snap, after including the gnome-3-34 extension the following warnings appeared on a cli startup of the snap:

Warning: Schema “org.gnome.system.locale” has path “/system/locale/”.  Paths starting with “/apps/”, “/desktop/” or “/system/” are deprecated.
Warning: Schema “org.gnome.system.proxy” has path “/system/proxy/”.  Paths starting with “/apps/”, “/desktop/” or “/system/” are deprecated.
Warning: Schema “org.gnome.system.proxy.http” has path “/system/proxy/http/”.  Paths starting with “/apps/”, “/desktop/” or “/system/” are deprecated.
Warning: Schema “org.gnome.system.proxy.https” has path “/system/proxy/https/”.  Paths starting with “/apps/”, “/desktop/” or “/system/” are deprecated.
Warning: Schema “org.gnome.system.proxy.ftp” has path “/system/proxy/ftp/”.  Paths starting with “/apps/”, “/desktop/” or “/system/” are deprecated.
Warning: Schema “org.gnome.system.proxy.socks” has path “/system/proxy/socks/”.  Paths starting with “/apps/”, “/desktop/” or “/system/” are deprecated.

maybe related or unrelated are the following warnings:

Gtk-Message: 10:56:59.134: Failed to load module "canberra-gtk-module"
Gtk-Message: 10:56:59.162: Failed to load module "canberra-gtk-module"

my snapcraft.yaml is as follows:

title: PhotoNoteBook
version: '1.2'
summary: A digital photography library manager and notebook 
license: Proprietary
description: PhotoNoteBook is a digital photograph library manager enabling collections of images and the making of notes and memo's for the collections and the photographs. 
icon: photonotebook.png 

confinement: strict
grade: stable
base: core18
 
apps:
  photonotebook:
    command: bin/photonotebook
    extensions:
      - gnome-3-34
    plugs: [home, unity7,  opengl, network, removable-media, optical-drive]
     

parts:
  photonotebook:
    plugin: dump
    source: ./photonotebook/
    stage-packages: [libfreetype6, libpng16-16, libx11-6, libxext6, libxi6, libxrender1, libxtst6, libasound2, libcanberra-gtk-module, libcanberra-gtk3-module ]

I cannot judge if these are “noise” or are significant.
Any help and advice anyone can provide will be gratefully received.

kind regards
Alan