The registry entry is for the startup.

If the keyboard reverts to "keyboard" when you select "Fitaly" it means the operating system failed to load "Fitaly" and decided to load "keyboard" instead.

Now why does it fail to load Fitaly, that's the question.
Not easy to track down why it works for a short while and then not.

Sorry to ask, but have you tried to load Fitaly after a soft reset when this happens?

Best regards,
Emmanuel