I have 4 language packs installed, as I need them for my work : FR, EN, DE and RU. So, I have 2 keyboard layouts installed: FR and RU.
However, RU layout seems to be wrong : no Cyrillic letters, but rather standard QWERTY US layout.
Thank you for your help.
Probably this Language switcher - #5 by fossfreedom
If it is resolved by that ppa then this is the bug report that is awaiting Canonical to process the fix i have uploaded today