Dear Scott,
A list of additional Russian vernacular names is here: https://docs.google.com/spreadsheets/d/1vKPE7Nq7mDWO6va9DsiF3eGfTUiaI4lHPsaJ2LQiiHA/edit?usp=sharing
The list contains only taxa with no Russian names in the original file. All together, 3,919 entries.
In the Moscow Digital Herbarium, we hold Russian names for global flora, not only for species occurring in Russia. If you send a list of global plant names without Russian translation in the same format, we can add them easily as well.
Hope, this helps.