12
Let's see if I can post this before Lawrie beats me to it 
(Disclaimer: I am American, hence I use the fractional note names.)
This is easy to correct, as follows:
!NoteWorthyComposerClip(2.751,Single)
|Clef|Type:Treble
|Key|Signature:Bb,Eb,Ab,Db,Gb,Cb|Tonic:G
|TimeSig|Signature:3/4
|Chord|Dur:4th|Pos:-4,-1|Opts:Stem=Down|Dur2:4th,Dotted|Pos2:2
|RestChord|Dur:8th|Opts:Stem=Up,ArticulationsOnStem,HideRest|Dur2:4th|Pos2:-2
|Note|Dur:8th|Pos:5|Opts:Stem=Up
|Chord|Dur:8th|Pos:4|Opts:Stem=Up,Beam=First|Dur2:4th|Pos2:-2,1
|Note|Dur:8th|Pos:3|Opts:Stem=Up,Beam=End
!NoteWorthyComposerClip-End
The thing to remember when you are using two parts per staff is that when you have two notes of different durations at the same position (like the dotted quarter stem up and plain quarter stem down), the duration that is reserved for that position is that of the shorter note. NWC created the "rest chord" as a way of dealing with this. A rest chord is basically a split chord where one of the two notes is a rest. Also, in a rest chord, the rest duration must be less than or equal to the note duration (i.e. you can't have a half rest and a quarter note.) So for your example, I change the lone quarter note to a rest chord with an eighth rest, which "steals" an eighth duration from the first two notes, so that the total duration is now 3 eighth beats, and the parts line up again.
You'll notice that the rest is shown greyed out. That is because a rest chord has an option of hiding the rest in the printout, since you don't always want to see them.
33
The help file for the Tremolo.ms object says the following:
I chose this approach for eighth note tremolos since there is no easy way to hide the flag on eighth notes 
Here is a fixed version of that measure. Also, please note that you should mute the notes on each side of the tremolo object if you are using playback.
!NoteWorthyComposerClip(2.751,Single)
|Chord|Dur:8th|Pos:-9,-2|Opts:Stem=Up,Beam=First
|Note|Dur:8th|Pos:-5|Opts:Stem=Up,Beam
|Chord|Dur:8th|Pos:-9,-2|Opts:Stem=Up,Beam
|Note|Dur:8th|Pos:-5|Opts:Stem=Up,Beam=End
|Spacer|Width:200
|RestChord|Dur:16th|Opts:Stem=Down,ArticulationsOnStem,Muted,HideRest|Dur2:4th|Pos2:-7|Color:1
|Spacer|Width:300|Color:1
|User|Tremolo.ms|Pos:-8|Color:1
|RestChord|Dur:16th|Opts:Stem=Down,ArticulationsOnStem,Muted,HideRest|Dur2:4th|Pos2:-2|Color:1
|Spacer|Width:375|Color:1
|Chord|Dur:4th|Pos:-9,-2
!NoteWorthyComposerClip-End
48
Try changing line 137 from:
x1s = x1s or x1+1.3
to:
x1s = x1s or priorNote:xyRight()
I am still testing to make sure it doesn't break anything.