IBus has support for the typical languages requiring an IME such as Japanese, Chinese (various) and Korean. See list below.
It has replaced SCIM as the IME frontend of choice for Ubuntu, since it's more actively developed. If you're not happy with IBus, SCIM is a mature alternative.
List of packages starting with ibus:
ibus-anthy ibus-table-cangjie3 ibus-table-rustrad
ibus-array ibus-table-cangjie5 ibus-table-scj6
ibus-chewing ibus-table-cangjie-big ibus-table-stroke5
ibus-clutter ibus-table-cantonese ibus-table-thai
ibus-el ibus-table-cantonhk ibus-table-translit
ibus-gtk ibus-table-cns11643 ibus-table-translit-ua
ibus-hangul ibus-table-compose ibus-table-viqr
ibus-input-pad ibus-table-easy ibus-table-wu
ibus-m17n ibus-table-easy-big ibus-table-wubi
ibus-mozc ibus-table-emoji ibus-table-xinhua
ibus-pinyin ibus-table-erbi ibus-table-yawerty
ibus-pinyin-db-android ibus-table-extraphrase ibus-table-yong
ibus-pinyin-db-open-phrase ibus-table-ipa-x-sampa ibus-table-zhuyin
ibus-qt4 ibus-table-jyutping ibus-table-ziranma
ibus-skk ibus-table-latex ibus-tegaki
ibus-sunpinyin ibus-table-quick ibus-unikey
ibus-table ibus-table-quick3 ibus-xkbc
ibus-table-array30 ibus-table-quick5
ibus-table-cangjie ibus-table-quick-classic
As for lo-gtk and th-gtk, I think they are for Lao and Thai respectively. See below:
$ locate lo-gtk
/etc/X11/xinit/xinput.d/lo-gtk
$ head -n3 /etc/X11/xinit/xinput.d/lo-gtk
#
# This configuration provides default IM setting for Lao with stock GTK+
# Thai-Lao input method.
$ head -n3 /etc/X11/xinit/xinput.d/th-gtk
#
# This configuration provides default IM setting for Thai with stock GTK+
# Thai-Lao input method.