caribou (gnome-shell osk): special characters not working

I'm on Ubuntu 17.10 (fully updated, including Gnome-Shell). Hardware is a Lenovo X1 Carbon Laptop with Touchscreen. I've reproduced this issue on both Wayland and XOrg. I've reproduced this issue on the 17.10 live CD (Xorg) and on a fresh 17.10 (Wayland) install in VBox.

Bug: Caribou/Gnome-Shell Wayland support for Caribou does not display the vast majority of special characters (the ones that you long press on vowels to get). Nor do the upside down question and exclamation marks work on it either. Nor do the Euro or Sterling signs work. This makes it impossible to use when writing in any other languages than English.

1) lsb_release -rd
Description: Ubuntu 17.10
Release: 17.10

2) package version:

caribou:
  Installed: 0.4.21-2
  Candidate: 0.4.21-2
  Version table:
 *** 0.4.21-2 500
        500 http://ca.archive.ubuntu.com/ubuntu artful/main amd64 Packages
        100 /var/lib/dpkg/status

gnome-shell:
  Installed: 3.26.2-0ubuntu0.1
  Candidate: 3.26.2-0ubuntu0.1
  Version table:
 *** 3.26.2-0ubuntu0.1 500
        500 http://ca.archive.ubuntu.com/ubuntu artful-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     3.26.1-0ubuntu4 500
        500 http://ca.archive.ubuntu.com/ubuntu artful/main amd64 Packages

3) What do I expect to happen: I expect that when I long press on e and get the popup and select ê, ë that these letter appear
4) they do not. nothing happens