Microsoft Translator only supports <Button id="Button1" runat="server">My Button</ Button>
translations. It doesn't translate the input type=button, asp:Button or telerik:Button nor any other flavor of buttons that you don't place the text for the button in between the tags. Check this article out.
I have been looking for a solution similar to what you are but I have found nothing.
So outside of changing all your buttons to this type I am assuming that we would need to use the api to do the translations.