My aim is to slow down the second time, so I tried this way:
!NoteWorthyComposerClip(2.51,Single)
|Clef|Type:Treble
|TimeSig|Signature:4/4
|Key|Signature:C|Tonic:C
|Dynamic|Style:f|Pos:-11
|Tempo|Tempo:100|Pos:8|Visibility:Never
|Bar|Style:MasterRepeatOpen
|Rest|Dur:8th
|Note|Dur:8th|Pos:-7|Opts:Stem=Up
|Chord|Dur:8th|Pos:-5,-2|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-7|Opts:Stem=Up,Beam=End
|Rest|Dur:8th
|Note|Dur:8th|Pos:-6|Opts:Stem=Up
|Chord|Dur:8th|Pos:-4,-2|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-6|Opts:Stem=Up,Beam=End
|Bar
|TempoVariance|Style:Ritardando|Pos:8|Visibility:Never
|Rest|Dur:8th
|Note|Dur:8th|Pos:-8|Opts:Stem=Up
|Chord|Dur:8th|Pos:-5,-3|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-8|Opts:Stem=Up,Beam=End
|Rest|Dur:8th
|Note|Dur:8th|Pos:-8|Opts:Stem=Up
|Chord|Dur:8th|Pos:-6,-4|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-8|Opts:Stem=Up,Beam=End
|Bar
|Ending|Endings:1|ClosedBracket:Y
|Rest|Dur:8th
|Note|Dur:8th|Pos:#-9|Opts:Stem=Up
|Chord|Dur:8th|Pos:-7,-4|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-9|Opts:Stem=Up,Beam=End
|Rest|Dur:8th
|Note|Dur:8th|Pos:-8|Opts:Stem=Up
|Chord|Dur:8th|Pos:-6,-4|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-8|Opts:Stem=Up,Beam=End
|Bar|Style:MasterRepeatClose
|Ending|Endings:2
|Rest|Dur:8th
|Note|Dur:8th|Pos:#-9|Opts:Stem=Up
|Chord|Dur:8th|Pos:-7,-4|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-9|Opts:Stem=Up,Beam=End
|Rest|Dur:4th
|Rest|Dur:4th
|Tempo|Tempo:50|Pos:8|Visibility:Never
|Bar
|Chord|Dur:Whole|Pos:-6,-4,-3
!NoteWorthyComposerClip-End
As you can ear, that's not the case.
To begin with, it slows down the first time too (why?).
Then, when it reaches the "ritardando" for the second time, all of a sudden it restores the standard time and then slows down. ()
I tried this way:
!NoteWorthyComposerClip(2.51,Single)
|Clef|Type:Treble
|TimeSig|Signature:4/4
|Key|Signature:C|Tonic:C
|Dynamic|Style:f|Pos:-11
|Tempo|Tempo:100|Pos:8|Visibility:Never
|Bar|Style:MasterRepeatOpen
|Rest|Dur:8th
|Note|Dur:8th|Pos:-7|Opts:Stem=Up
|Chord|Dur:8th|Pos:-5,-2|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-7|Opts:Stem=Up,Beam=End
|Rest|Dur:8th
|Note|Dur:8th|Pos:-6|Opts:Stem=Up
|Chord|Dur:8th|Pos:-4,-2|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-6|Opts:Stem=Up,Beam=End
|Bar
|TempoVariance|Style:Ritardando|Pos:8|Visibility:Never
|Rest|Dur:8th
|Note|Dur:8th|Pos:-8|Opts:Stem=Up
|Chord|Dur:8th|Pos:-5,-3|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-8|Opts:Stem=Up,Beam=End
|Rest|Dur:8th
|Note|Dur:8th|Pos:-8|Opts:Stem=Up
|Chord|Dur:8th|Pos:-6,-4|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-8|Opts:Stem=Up,Beam=End
|Bar
|Ending|Endings:1|ClosedBracket:Y
|Tempo|Tempo:100|Pos:8|Visibility:Never
|Rest|Dur:8th
|Note|Dur:8th|Pos:#-9|Opts:Stem=Up
|Chord|Dur:8th|Pos:-7,-4|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-9|Opts:Stem=Up,Beam=End
|Rest|Dur:8th
|Note|Dur:8th|Pos:-8|Opts:Stem=Up
|Chord|Dur:8th|Pos:-6,-4|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-8|Opts:Stem=Up,Beam=End
|Bar|Style:MasterRepeatClose
|Ending|Endings:2
|Rest|Dur:8th
|Note|Dur:8th|Pos:#-9|Opts:Stem=Up
|Chord|Dur:8th|Pos:-7,-4|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-9|Opts:Stem=Up,Beam=End
|Rest|Dur:4th
|Rest|Dur:4th
|Tempo|Tempo:50|Pos:8|Visibility:Never
|Bar
|Chord|Dur:Whole|Pos:-6,-4,-3
!NoteWorthyComposerClip-End
With my great surprise, now it never slows down.
It seems that the tempo indications are not subjected to the special endings parser.