I’m not sure where to post an LSR bug report but maybe the people
responsible for the LSR read this list?
Snippet 318 (http://lsr.di.unimi.it/LSR/Item?id=318) states that
\parenthesize for notes works only inside chords. That’s not correct,
the following works as expected in 2.12.3 and newer versions (I haven’t
tested older ones):