Explain the problem as you see it
NewsReader typeface doesn't have a Cyrillic subset, so when a page with Cyrillic glyphs is Published using Serif typeface option -- it looks weird.
Why is this a problem for you?
My own motivation to do this – sometimes I want to use serif publishing with a cyrillic texts, but I can't as it looks awful right now (latin letters are ok, but Cyrillic glyphs look weird).
Suggest a solution
How about I add Cyrillic to NewsReader typeface Tana uses for serif type in publishing? It is an open typeface at fonts.google so modifying it will be in compliance with its licence.