Usually the iOS app pronounces Russian words and phrases very well. I have noticed that sometimes the quality is suddenly degraded - as if an English speaker with no knowledge of Russian is sounding the words out using English phonetics.
This issue seems to appear after editing sentences. An app restart restores quality.
I thought it always happened after editing a sentence. Not true. Seems to sometimes degrade randomly - sometimes only for one word - usually a long one (Russian) - sometimes consistently until I restart the app.