Thanks - yes I've had feedback like that about the rests and have since tidied it up - consolidated some of the rests and replaced others with breath marks. I hadn't realised how difficult all these tiny rests would make it for the singers.
It might be a bit harsh to say "the whole system is flawed". As it's written atonally (as opposed to tonally but constantly switching tonal centres), I understand there are different and much simpler conventions for enharmonics - but I'm using them for the first time so wasn't sure I was getting it right. It seems that there is no key signature, and the expected enharmonics seem to revolve around ensuring horizontal readability (e.g. avoiding where possible consecutive different notes in the same line). I understand that if looked at through a tonal lens, it might seem overwhelming, but it's not a tonally written piece.
I could share the web page where the track in embedded so that it's much easier to hear. I'll bear that in mind for the future, but I'm not sure I'm going to be posting any more music on forums. While I've had some excellent support and advice that's really thrown light on my blind spots and helped me to move forwards, there's also been (not here) plenty of small-minded, finger-wagging abuse, which is really disheartening and demotivating, and sadly, I don't think it's worth it anymore. This seems unfortunately to be the norm, and I've come across several composers who've either stopped sharing or given up composing all together because of it.