While I may not necessarily be in love with the intro to first bit of verse in terms of performance (I feel they could have been a bit more confident is all!) as soon as all comes together with the two of you singing proud, song is gold!
There are a few issues where on multiple takes I can hear dead mic noise. Noise reduction in RX7 or another softwhere which will allow you to learn deadnoise pattern and intelligently remove it from the signal will usually do the trick without damaging the takes as EQ or multiband might. I experimented with my own airconditioner ruined takes, and 2 passes did it, learning the silent portions between for each. The worry prone such as myself will do well to save a copy prior and save over the file with the noiseless version thereafter.
I actually think the balance toward Trois' choral portions could be a bit more open. At present she is hiding in the mix on the bigger vocal sections, when I would really love to hear that free, breathy quality there hiding in the mix. Potentially bring Chris and the guitars down just a tad to make room for her? Hmm..
Beyond that on larger sections the dead noise does come into play where there are multiple takes and cuts, but again you are working with TONS of them in the project so this is understandable. You're doing an older chorus method, overdubs and so on, so there is going to be lots of noise, and it's hard to be rid of all of it!
In terms of instrumentation, composition, and lyrics, and all elements brought to the fore save what I have already mentioned, you two have brought to the table something so, so special. Working absolute magic over there across the pond. Fantastic work, and as always, lovely to hear from you <3