The ibus-unikey behavior in this respect is not configurable AFAIK. While the behavior is fine together with latin keyboard layouts, it's problematic when you try to switch from a non-latin layout such as Russian directly to Unikey.
You have found a workaround — switch to English first, then Unikey — which is good.
The upstream development of ibus-unikey has stopped, so the chance is small that the issue will be addressed soon.
Thanks for your report.
The ibus-unikey behavior in this respect is not configurable AFAIK. While the behavior is fine together with latin keyboard layouts, it's problematic when you try to switch from a non-latin layout such as Russian directly to Unikey.
You have found a workaround — switch to English first, then Unikey — which is good.
The upstream development of ibus-unikey has stopped, so the chance is small that the issue will be addressed soon.