I can’t recommend enough to write your own rule summary. Write it once, and reorganize it as much as you can with the goal to teach it in a fluent way. Teaching also means giving few components to players when you explain them, simulate actions physically (When you say I draw a card, you draw a card, When you say I push ressource A token here, you push the token, etc.).
With heavy games, players expect the owner to be a teacher. Not everyone is good at this. The owner role is to ensure peoples don’t spend a bad time with the game. Teaching the rules in a engaging way is part of owner responsibility.
This is how I take it. I have few heavy game but I try to learn rules and learn to teach rules as much as I can so players feel confident after first turn.