Workarounds: 

1. Use Web Service binding where the issue is not observed

2. Use the following workaround that could make the text of the button "Edit Recurrence" every time

function OnClientFormCreated(sender, args) {
    // it is in Mobile rendering
    if (sender.get_renderMode() == 4) {
        var $ = $telerik.$,
        $T = Telerik.Web.UI,
        $TRE = $T.SchedulerRecurrenceEditor;
  
        var $recurrenceToggle = $(".rsAdvRepeat");
        $recurrenceToggle.text("Edit Recurrence");
  
        // If you use this workaround, the text will be always "Edit Recurrence"
        $TRE.NativeView.prototype._updateRecurrenceButtonText = function () {
            var $recurrenceToggle = $(this._getElement("AppointmentRepeat"));
            $recurrenceToggle.text("Edit Recurrence");
        }
    }
}

If you do not override the _updateRecurrenceButtonText and only set the recurrenceToggle text, then you could have the correct value as the button text when you click the button and then select a new recurrence rule.