When you consider what it's meant to do, it is actually pretty logical. 3/4" spacing for the main jack if you run the speaker full-range, and jumpers to connect all the speaker drivers into the crossover network. Pull the appropriate jumpers, and you have 3/4" spacing jacks to plug an amplifier into the appropriate drivers directly for biamplification of the speaker. Also, the connections which should not be accidentally shorted are far enough apart that you can't plug a standard 3/4" dual banana into them. If you're really industrious, you have access to all the drivers and crossover components, in case you want to just put an attenuator into the tweeter circuit (a real option for the 1-D and IV models) or replace any of the crossover elements individually.
I actually like it better than the old style (pictured; not mine but similar) which requires you to use spade connectors and/or bare wire and short the jumper terminals with fiddly little bits of resistor lead.

Same functionality but messy.
Back on the subject of wire gauge, I still haven't found a good reference for small aluminum wire, but a variety of sources suggest using 2 AWG sizes larger for aluminum vs. copper. This points to an approximate current rating of about 20mA for AWG35 aluminum, which I suspect is wildly conservative. Even allowing for the fact that the tweeter is 2 parallel runs of 16Ω wire, that's not a lot of current and I know I've pushed over 1A through them with no damage. That's the typical fuse value for one of these, I'm guessing. The IV and 1-D are 4Ω systems of similar design and I know they come with a 2A fuse.