Peter, believe me, I get your thoughts and maybe a bit of frustration on the way things are somewhat hap-hazardly thrown together here. This has been a subject of my ultimate frustration as well on things in the past regarding "quality of build".
I could go on about this very thing, but will not, as it doesn't do any good to harp on it, and in the end, I still think the Ohms are very good sounding speakers and maybe some of this has absolutely no bearing on sonics. I will say this, at least your can/switch/wiring/crossover assembly there do look a decent deal better than what I have witnessed in the past, for whatever that is worth.
As to the cabinet blocking part of the driver, while in theory maybe not a good idea at all, and maybe a general lack of attention to detail etc., keep in mind that most of the sound/music is being driven outwards from the cone surface and not so much down, and I doubt that there is much if any real "loss" of information due to the cabinet not being perfect. But, perfectionists to a fault maybe some of us are.
I will be interested in your electronic crossover here, as I do think utilizing active crossovers can yield some good results. Not always though, and sometimes it ends up being more complex in the end, which may be the case with the Ohms here, but worth a try!
Thanks for the pics along the way too, that to me is the most interesting part for several reasons....Will continue to watch this space!