private void T_Tick(object sender, EventArgs e)
        {
            t.Stop();
            Cursor.Position = new Point(0,0); 
        }

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik

        Timer t = null;
        Point point = Point.Empty;
        private void radVirtualKeyboard1_KeySent(object sender, Telerik.WinControls.VirtualKeyboard.VirtualKeyboardKeySentEventArgs e)
        {
            RadItem item = e.Key as RadItem;
            if (item != null)
            {
                point = this.radVirtualKeyboard1.PointToScreen(item.ControlBoundingRectangle.Location);
                t = new Timer();
                t.Interval = 1000;
                t.Tick += T_Tick; t.Start(); 
                System.Media.SystemSounds.Beep.Play();
            }
        }

        private void T_Tick(object sender, EventArgs e)
        {
            t.Stop();
            point.X--;
            point.Y--;
            Cursor.Position = point; 
        }

I have also updated your Telerik points.

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik

Hello, Yannis,

Every RadControl tracks for the WM_GESTURE message. This message is not received on touch devices but is translated to mouse events and we cannot determine whether the click comes from Mouse or Touch gesture. Why does the button state is MouseOver after a tap on a touch device? Because when tapping, the control receives click/mouse up/down event/s and mouse position is changed over the button. The highlight comes from the hover state for the key.

I confirm that it is an issue with RadVirtualKeyboard and I have logged it in our feedback portal by making this thread public. You can track its progress, subscribe for status changes and add your comments on the following link - feedback item.

I have also updated your Telerik points.

Currently, the possible solution that I can suggest is to simulate moving the mouse outside the tapped key: 

        private void radVirtualKeyboard1_KeySent(object sender, Telerik.WinControls.VirtualKeyboard.VirtualKeyboardKeySentEventArgs e)
        {
            RadItem item = e.Key as RadItem;
            if (item != null)
            {
                Point point = this.radVirtualKeyboard1.PointToScreen(item.ControlBoundingRectangle.Location);
                point.X--;
                point.Y--;
                Cursor.Position = point;
            }
        }

As to the repeat button's functionality, due to the specificity of the mouse/touch messages that are received on a touch device, I am unable to provide a suitable solution. We will do our best to introduce a fix accordingly. Please excuse us for the inconvenience caused.

Playing a sound when you click a button is more like a general programming question. After some research, I have found the following useful StackOverflow thread which demonstrates a simple solution which I believe you would fit your case: https://stackoverflow.com/questions/23643468/how-do-i-code-my-winforms-application-play-a-system-sound 

I hope this information helps. If you need any further assistance please don't hesitate to contact me. 

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik