Is there anyone who knows the code to assign a specific Support Acu unit to focus only on assisting a specific factory?
SupportACU Focus Assist Codes
Are you talking about the user interface in game? You can select any unit with engineering and then right-click on a factory. This will become an "assist" order. A unit that has an "assist" order on a specific factory will help that factory to make things faster.
Are you talking about programming AI? There is a separate subforum for AI development and you can get help faster in the maps & mods discord.