Yup, very hard indeed. Like Darla, NHO 7, and I do think that Enigmatist could have given us non-techies a bit more help with that one.
And I’ve completely failed to parse 11 despite having stared at it until my eyes glazed over.
All done, but a real struggle.
FOI 8, which I really liked but which didn’t help as much as I’d hoped.
LOI 11, only because I finally entered it reluctantly as it was the only possible solution, but without parsing it.
COD? Well I liked 23d