Hmm, that would be because I used the wrong font - D'oH
Try this:
!NoteWorthyComposer(2.0)
|SongInfo|Title:""|Author:"<Name>"|Lyricist:""|Copyright1:"Copyright © 2009 <Name>"|Copyright2:"All Rights Reserved"
|PgSetup|StaffSize:20|NtnTypeface:NWC2MusikDingsSerif|Zoom:5|TitlePage:Y|JustifyVertically:Y|ExtendLastSystem:N|DurationPadding:Y|PageNumbers:0|StaffLabels:None|BarNumbers:None|StartingBar:1|AllowLayering:Y
|Font|Style:Staff Italic|Typeface:"MusikTextSerif"|Size:12|Bold:Y|Italic:Y|CharSet:2
|Font|Style:Staff Bold|Typeface:"MusikTextSerif"|Size:12|Bold:Y|Italic:N|CharSet:2
|Font|Style:Staff Lyric|Typeface:"MusikTextSerif"|Size:12|Bold:N|Italic:N|CharSet:2
|Font|Style:Page Title Text|Typeface:"MusikTextSerif"|Size:24|Bold:Y|Italic:N|CharSet:2
|Font|Style:Page Text|Typeface:"MusikTextSerif"|Size:12|Bold:N|Italic:N|CharSet:2
|Font|Style:Page Small Text|Typeface:"MusikTextSerif"|Size:8|Bold:N|Italic:N|CharSet:2
|Font|Style:User 1|Typeface:"MusikDingsSerif"|Size:14|Bold:N|Italic:N|CharSet:0
|Font|Style:User 2|Typeface:"Times New Roman"|Size:8|Bold:N|Italic:N|CharSet:0
|Font|Style:User 3|Typeface:"Times New Roman"|Size:8|Bold:N|Italic:N|CharSet:0
|Font|Style:User 4|Typeface:"Times New Roman"|Size:8|Bold:N|Italic:N|CharSet:0
|Font|Style:User 5|Typeface:"Times New Roman"|Size:8|Bold:N|Italic:N|CharSet:0
|Font|Style:User 6|Typeface:"Times New Roman"|Size:8|Bold:N|Italic:N|CharSet:0
|PgMargins|Left:1.27|Top:1.27|Right:1.27|Bottom:1.27|Mirror:N
|AddStaff|Name:"Staff"|Group:"Standard"
|StaffProperties|EndingBar:Section Close|Visible:Y|BoundaryTop:12|BoundaryBottom:12|Lines:5|Style:Standard|Layer:N|Color:Default
|StaffProperties|Muted:N|Volume:127|StereoPan:64|Device:0|Channel:1
|StaffInstrument|Trans:0|DynVel:10,30,45,60,75,92,108,127
|Clef|Type:Treble
|Key|Signature:F#
|Tempo|Tempo:200|Pos:12
|TimeSig|Signature:4/4
|Note|Dur:8th|Pos:5|Opts:Stem=Down,Beam=First
|Note|Dur:8th|Pos:4|Opts:Stem=Down,Beam=End
|Note|Dur:8th|Pos:n4|Opts:Stem=Down,Beam=First
|Note|Dur:8th|Pos:3|Opts:Stem=Down,Beam=End
|Note|Dur:8th|Pos:b3|Opts:Stem=Down,Beam=First
|Note|Dur:8th|Pos:2|Opts:Stem=Down,Beam=End
|Note|Dur:8th|Pos:b2|Opts:Stem=Down,Beam=First
|Note|Dur:8th|Pos:1|Opts:Stem=Down,Beam=End
|Bar
|Note|Dur:8th|Pos:0|Opts:Stem=Down,Beam=First
|Note|Dur:8th|Pos:b0|Opts:Stem=Down,Beam=End
|Note|Dur:8th|Pos:-1|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:b-1|Opts:Stem=Up,Beam=End
|Note|Dur:8th|Pos:-2|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-3|Opts:Stem=Up,Beam=End
|Note|Dur:8th|Pos:n-3|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-4|Opts:Stem=Up,Beam=End
|Bar
|Text|Text:"²"|Font:User1|Pos:-3|Wide:Y|Justify:Right
|Note|Dur:4th|Pos:-3
|Note|Dur:8th|Pos:-3|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-3|Opts:Stem=Up,Beam=End
|Note|Dur:4th|Pos:-3
|Note|Dur:4th|Pos:-3
|Bar
|Note|Dur:8th|Pos:-3
|Rest|Dur:8th
|Note|Dur:8th|Pos:-3
|Rest|Dur:8th
|Rest|Dur:Half
|Bar
|Note|Dur:4th|Pos:4
|Note|Dur:8th|Pos:4|Opts:Stem=Down,Beam=First
|Note|Dur:8th|Pos:4|Opts:Stem=Down,Beam=End
|Note|Dur:4th|Pos:4
|Note|Dur:4th|Pos:4
|Bar
|Note|Dur:8th|Pos:4
|Rest|Dur:8th
|Note|Dur:8th|Pos:4
|Rest|Dur:8th
|Rest|Dur:Half
|Bar
|Text|Text:"²"|Font:User1|Pos:-3|Wide:Y|Justify:Right
|Note|Dur:8th|Pos:-3
|Text|Text:"´"|Font:User1|Pos:-3|Wide:Y|Justify:Right
|Note|Dur:8th|Pos:-3
|Text|Text:"¹"|Font:User1|Pos:-3|Wide:Y|Justify:Right
|Note|Dur:8th|Pos:-3
|Text|Text:"³"|Font:User1|Pos:-3|Wide:Y|Justify:Right
|Note|Dur:8th|Pos:-3
|Text|Text:"×"|Font:User1|Pos:-3|Wide:Y|Justify:Right
|Note|Dur:8th|Pos:-3
!NoteWorthyComposer-End
As for the size, perhaps I could have been more careful when I set this up. I no longer recall what criteria I used to for these glyphs as I usually expect to see the *Dings fonts at 100% of staff metrics. It may well be that like my Coda and Segno glyphs (I like some things to be quite large so they aren't easy to miss when sight reading and one hasn't really had much time to study the score) I wanted them to be very visible...