Relationships Calendar is in Russian - How do I fix?
I've tracked down what caused the - duplicate calendar icons . It was an outdated version of the CiviCRM Shoreditch extension that was installed. I've disabled, uninstalled and deleted it. The duplicate icons are gone, the Russian text still remains though.

I have posted a ticket on the Shoreditch extension github site with the details. Hopefully they can resolve the issue. In the meantime, i've disabled the extension.