Mh. I think the scripting part is currently about finishing the new interaction menu (inventory + buying + selling + production) that we layed out at the last CM (there are some sketches of Matthi).
The status is that the framework (big menu, showing smaller menu-parts with callbacks) and the inventory menu work. So building should be able to insert their menus into that main menu via callbacks. An unsolved issue is how to refresh those open menus - not so much the "how" but more the "when": how are changes detected with the least work for the producer (aka "with the easiest interface").

This, of course, is a major GUI scripting part *). If someone wanted to get used to the GUI things as the first step, one possibility would be to change the gold display in the top-right corner to use the new menu interface, or add a HP bar on the left, or change the crew selection buttons to use the new menus. All this stuff is obviously low priority because things also work without it. But it might be a good start to get used to the menu interface.

*) It at least requires understanding of the GUI stuff, even if most of the tricky script work is already done (aka, "how do I maintain a framework-menu with sub-entries").

PS: the next engine stuff I have to do is probably adjusting the menu stuff to use the old C4GUI. For the greater good in the long run™.
PPS: but I will at least be semi-busy with my bachelor's thesis in the next two months. That's why I said I probably won't do anything of the bigger (engine-work) stuff in the next time.