There are several clean installations, archlinux + xfce4. Been using for several years, recently noticed that when switching the layout, some characters are not typed. The situation is the same with both windows and linux clients. The next time I logged in, they might change into different characters. Usually it’s: “фэцмитьхъ.”
Hello @chupa and welcome to the forum!
As ThinLinc is symbol-based and not key based, you can unfortunately end
up with different key codes being generated. If you make sure to use
the same keyboard layout on the client and inside the session, then you
should get better behavior.
You can set the desired default layout in ThinLinc by modifying keyboard_layout in /opt/thinlinc/etc/conf.d/sessionstart.hconf. Don’t forget to issue a $ sudo systemctl restart vsmagent and restart your session afterward.
This setting might be overwritten by your desktop environment, so make sure you configure your DE for this layout as well.
Does this help with the problem for you?
Kind regards,
Martin
I changed [keyboard_layout] to “ru”, now сyrillic characters are fully typed. But when you switch the layout to en, “tyi” or “bnm” stop typing. The layout is switched only on the client.
Switching between keyboard layouts (especially those that differ a lot, like ru and en) is not something that works particular well with ThinLinc, unfortionatley 
This is a known limitation and it is being tracked in the ThinLinc Bugzilla:
https://bugzilla.cendio.com/show_bug.cgi?id=7540
Regards,
Martin