The problem with the tooltips is that they were being added to the <a ..> tag using the name of the control, not the actual help text (in PropertyLabelControl.vb):

 Public Property Caption() As String
    Get
        Me.EnsureChildControls()
        Return lblLabel.Text
    End Get
    Set(ByVal Value As String)
        Me.EnsureChildControls()
        lblLabel.Text = Value
        cmdHelp.ToolTip = Value
    End Set
End Property

The solution is to comment this line and add the tooltip to the image in the same way the text is attached to the label and help text:

Public Property ResourceKey() As String
    Get
        Return _ResourceKey
    End Get
    Set(ByVal Value As String)
        _ResourceKey = Value

        Me.EnsureChildControls()

        'Localize the Label and the Help text
        lblHelp.Attributes("resourcekey") = _ResourceKey + ".Help"
        imgHelp.Attributes("resourcekey") = _ResourceKey + ".Help"
        lblLabel.Attributes("resourcekey") = _ResourceKey + ".Text"

    End Set
End Property

Give it a try if you have a moment. I've tested this and seems to solve the problem.