Ubuntu – IBus XKB engine layouts don’t work

I have IBus installed on Lubuntu 18.04.1 64-bit, and some languages work properly, while others just have the US English layout.

The Hangul Korean input engine (ibus engine output hangul) works (al gives 미 in Hangul mode), but Swedish and Spanish XBD input (ibus engine output xbd:se::swe and xbd:es::spa, respectively) do not (the keyboard layout is exactly the same as US).

The m17n:sv:post postfix Swedish layout seems to work (oe gives ö).

This leads me to believe that there is a problem involving xkb IBus engines on my computer (whatever that means).

The output for dpkg -l | grep ibus | grep -v libusb is:

ii  gir1.2-ibus-1.0:amd64                   1.5.17-3ubuntu4                             amd64        Intelligent Input Bus - introspection data
ii  ibus                                    1.5.17-3ubuntu4                             amd64        Intelligent Input Bus - core
ii  ibus-gtk:amd64                          1.5.17-3ubuntu4                             amd64        Intelligent Input Bus - GTK+2 support
ii  ibus-gtk3:amd64                         1.5.17-3ubuntu4                             amd64        Intelligent Input Bus - GTK+3 support
ii  ibus-hangul                             1.5.0+git20161231-1                         amd64        Hangul engine for IBus
ii  ibus-m17n                               1.3.4-5                                     amd64        m17n engine for IBus
ii  ibus-qt4                                1.3.3-1build2                               amd64        qt-immodule for ibus (QT4) (plugin)
ii  ibus-table                              1.9.14-3                                    all          table engine for IBus
ii  libibus-1.0-5:amd64                     1.5.17-3ubuntu4                             amd64        Intelligent Input Bus - shared library
ii  libibus-1.0-dev:amd64                   1.5.17-3ubuntu4                             amd64        Intelligent Input Bus - development file
ii  libibus-qt1                             1.3.3-1build2                               amd64        qt-immodule for ibus (QT4) (library)
ii  libusageenvironment3:amd64              2018.02.18-1                                amd64        multimedia RTSP streaming library (UsageEnvironment classes)

The output for ibus list-engines (removed other languages):

...
language: Swedish
  xkb:se:dvorak:swe - Swedish (Dvorak)
  xkb:se:svdvorak:swe - Swedish (Svdvorak)
  m17n:sv:post - post (m17n)
  xkb:se::swe - Swedish
...
language: Korean
  hangul - Hangul
  m17n:ko:romaja - romaja (m17n)
  m17n:ko:han2 - han2 (m17n)
...
language: Spanish; Castilian
  xkb:es::spa - Spanish
  xkb:latam::spa - Spanish (Latin American)
...
language: English
  xkb:us::eng - English (US)
  xkb:gb:dvorak:eng - English (UK, Dvorak)
  xkb:gb:extd:eng - English (UK, extended WinKeys)
  xkb:us:altgr-intl:eng - English (international AltGr dead keys)
  xkb:us:colemak:eng - English (Colemak)
  xkb:us:dvorak:eng - English (Dvorak)
  xkb:ca:eng:eng - English (Canada)
  xkb:us:intl:eng - English (US, international with dead keys)
...

output for setxkbmap -query (same for all IBus layouts, even the non-US ones that work):

rules:      evdev
model:      pc105
layout:     us
variant:    ,
options:    grp:shift_caps_toggle