Malte, I've updated the Items page with a "colorized" graphic that divides these metadata components functionally. It's hard for me to see how any of these pieces are "optional". They all look mandatory to me.
Re your specific points:
- a sort_order on as_item_help_map may not be necessary, but it doesn't hurt anything either. What mapping table doesn't benefit from a sort_order column?
- a locale column in as_messages makes sense and is now there.