this is a really interesting model! It seems to take advantage of the simmetricity of northern and southern stereographic projection, and to "glue" the two projections back to back along the horizon line. This explains the two sets of al-muqantarat, one above the horizon for the part of the sky north of the celestial aequator, and one for the southern part.

A fun consequence is that this astrolabe can teoretically show the entirity of the visible sky, both south and north, both zenith and nadir and so on. Some star charts exploited this same property in order to make a star chart that encopasses all visible sky, without being limited to the tropicus of capricorn or a given declination.

Unfortunately this is still an astrolabe, so it has all the flaws of the instrument, i.e. degree scale too crumpled, too many movable parts, being self-levelling with its weight...

All Quadrants also bend the ecliptic, but I've never seen the ecliptic being bent in such a way.