Again, what's important to avoid is that Russian Orthodox church leaders campaign only in Russian neighbourhoods, among Russian populations, because if that happens, the signal is exactly the reverse of what you're talking about: it's divisive and it aligns church with language and ethnicity.
What you're looking to preserve is that multi-faith, multi-language forum that welcomes everybody and sends a message that they, as religious leaders in Ukraine, see the future of Ukraine as multilingual, multi-religious, multi-ethnic. That's the reassuring message.