Just a little hack to fix the Extension menu sorting in Robofont 1.8 + High Sierra

SortExtentionMenu_HighSierraHotFix.py

# fix the Extentions menu sorting in macOS High Sierra in Robofont 1.8
# (set this up as a start up script and you're good to go)

# This is just a hack, you should really check out RoboFont 3


from AppKit import *
from lib.doodleMenus import BaseMenu

# ----------------------------------------

def sort_menu_items(menu):
    controller = BaseMenu()

    # collect the different sub parts
    parts = []
    sub_parts = []
    for i in menu.itemArray():
        if i.hasSubmenu():
            sort_menu_items(i.submenu())
        if i.isSeparatorItem():
            sub_parts.append(i)
            parts.append(sub_parts)
            sub_parts = []
        else:
            sub_parts.append(i)
    parts.append(sub_parts)

    # sort the menu items
    sorted_parts = []
    for sub_parts in parts:
        
        # get the separator out
        if len(sub_parts) > 0 and sub_parts[-1].isSeparatorItem():
            sep = sub_parts.pop(-1)
        else:
            sep = None
            
        # keep alternates together with their parent when applicable
        sub_parts_with_alternates = []
        for p in sub_parts:
            if not p.isAlternate():
                sub_parts_with_alternates.append([p]) 
            else:
                sub_parts_with_alternates[-1].append(p)
        # sort 
        sub_parts_with_alternates.sort(key=lambda alts: alts[0].title())
        # flatten the [parent, alternate] couples
        sub_parts_flat = [item for sublist in sub_parts_with_alternates for item in sublist]
        
        # and put the separator back in
        if sep:
            sub_parts_flat.append(sep)
            
        sorted_parts += sub_parts_flat

    # rebuild the menu
    menu.removeAllItems()
    controller.buildAdditionContextualMenuItems(menu, sorted_parts)   

# ----------------------------------------

menuBar = NSApp().mainMenu()
ExtMenu = menuBar.itemWithTitle_("Extensions")
menu = ExtMenu.submenu()
sort_menu_items(menu)