Thank you for writing.
Currently, there is no way to change the encoding of the exported files. I have added it as a feature request in our Public Issue Tracking System - PITS
. You can track its progress, subscribe for status changes and add your vote/comment to it on the following link - PITS Feature.
I have also updated your Telerik points for the good suggestion.
I hope this is useful. Should you have further questions, I would be glad to help.
the Telerik team