You do realize Bert Jebsen, Gracie and Wong are this books little easter eggs aka Sue aka Johnny Cash, Right?
All these characters are from Big Trouble in Little China, Bert is Jack Burton not only does he look like jack but some of his abilities reflect this aka " All in the Reflexes" and "Big Talker". While Gracie is based off Gracie Law in name only and Jacks Big Rig, The Porkchop Express. While Wong is Wang Chi/Egg Shen, Wang was Jacks best friend and Wong's abilities are more in tune with Egg Shen with a "3 Demon bag" and a "Magical Iron Fan or something I can't recall". SO Wong is based off of 2 Asian characters in an awesome movie, wouldn't really say that's stereotyping, more of a homage if anything.