Fixed, and live now. Mr. Do had no dialogue because his whole pharmacy was never built. In v83 he's a script NPC: he makes medicine from herbs, and he's the only source of the Peach Tree Herb Pouch that Protecting the Peach Tree needs. So the quest couldn't be finished. He now has his full menu: make medicine (after you've learned from his book), make scrolls, donate ingredients, and the free replacement pouch if you lost the book. Please re-test the Peach Tree quest with him.