5 Right ending of slur is too far right.
7 [I did make a better test .ly for this, but can't seem to find it
11 \notes \relative c'' {
12 \property Voice.Stem \set #'direction = #1
13 \property Voice.Slur \set #'direction = #1
15 \property Voice.Slur \set #'attachment = #'(stem . stem)