The main issue over the past month is getting the different map types to work. Gen 5 introduced a non-grid (I called this "3d maps" in the last PTS notes) style of map which took a while to figure out. See:
(Obviously this isn't complete due to a lack of camera angle support)
Beyond that, the next major issue is world scripting. We understand most of the NDS's scripting language, but there are a few event-specific triggers we don't understand yet. I think the next PTS would be around the time when we have the basic world scripting completed.