In addition to what @hmmueller has said, there are additional things you can do, if you also insert a Marker object before the third triplet note. When both markers are present, you can change the angle of the triplet bracket. Building on Rick's example:
!NoteWorthyComposerClip(2.751,Single)
|Note|Dur:4th,Triplet=First|Pos:0
|Note|Dur:4th,Triplet|Pos:0
|Note|Dur:4th,Triplet=End|Pos:0
|Marker|Pos:0|Target:Triplet
|Note|Dur:4th,Triplet=First|Pos:0
|Note|Dur:4th,Triplet|Pos:0
|Note|Dur:4th,Triplet=End|Pos:0
|Marker|Pos:7.5|Target:Triplet
|Note|Dur:4th,Triplet=First|Pos:4
|Note|Dur:4th,Triplet|Pos:6
|Marker|Pos:11|Target:Triplet
|Note|Dur:4th,Triplet=End|Pos:8
!NoteWorthyComposerClip-End