It seems likely that I'll have to make my own vocal score of the piece a page of which is in the attached screenshot. I did start by making a draft vocal score as I went along, but inevitably have abandoned that idea.
Anyway, the page shown looks simplicity itself (

= 60) until you notice that on the last beat of the first system the clarinet has F natural (written as G) while the piano continues to have F sharp. This should sound as I wish when played as scored, but in any piano reduction I fear it might sound rather muddy, which without the security of the viola doubling might be disconcerting for the singer.
The score is full of this sort of thing, likely to create a frisson or tension as scored, but at risk of sounding more like a mistake in a piano reduction.
Any advice from members of this forum on how best to realize this in the vocal score will be appreciated.
BTW it's for this unlikely seeming commission, involving my near pastiche of a mix of musical languages
https://www.deveron-projects.com/b-means-b/ I'm actually finding it great fun to write.