Selection refusing to 'unselect' the superscript button (ctrl shift plus-sign)

[macropod]

It seems the statement:
Text = " "

Would insert space, if the macro is executed in the middle of sentence, which is undesirable.

Well, you wouldn't be concerned about whether the selection remains hyperlinked if you weren't about to do some more typing. As it is, the inserted space is left selected so it can be overtyped with whatever you want to have follow the hyperlink.

Also, if set the font of the sentence is set to a non-default (Calibri 11) to a different one (Times New Roman 12), Font.Reset, reverts to Calibri 11, instead of Times New Roman 12.

That's a self-inflicted problem caused by you not using Styles properly. You can revert to your own font capture & restoration code if you prefer.

Also I would only like the text inside of the square brackets to be hyperlinked.

In that case, use something along the lines of:

Sub Demo()
Dim Rng As Range
Const websiteName As String = "VBA Express"
Const Hyperlink As String = "http://www.vbaexpress.com/forum/showthread.php?66803-Selection-refusing-to-unselect-the-superscript-button-(ctrl-shift-plus-sign)"
    Set Rng = Selection.Range
    With Rng
        .Collapse wdCollapseEnd
        .Hyperlinks.Add Anchor:=.Duplicate, TextToDisplay:=websiteName, Address:=Hyperlink
        .End = .End + 1
        .End = .Hyperlinks(1).Range.End
        .InsertAfter "]"
        .InsertBefore "["
        .Font.Size = 14
        .Font.Superscript = True
        .Collapse wdCollapseEnd
        .Text = " "
        .Font.Reset
        .Select
    End With
End Sub