Just had lunch at Penang in Arlington Heights today. We had an absolutely delightful waiter -- not fluent English, but enough to be both enthusiastic and helpful. As I ordered, he'd say, "You like spicy? This better." He then directed me to a dish with Chinese sausage and squid -- so no "warning away" now, at least not today. It was not killer spicy, but was plenty hot for me ("we make all medium hot," I had been assured -- but that implies more heat is possible, for those who wish it).
Indonesian foods (and food words) were largely lifted from Malaysia, so I was pleased to see foods that were familiar from travels in Indonesia, including pandan chicken, ayam (chicken) rendang, cendol, and ice kecang (and if they don't warn you away from a dessert that involves shaved ice, red beans, sweet corn, and strips of pandan jelly, I don't think they're worried about your reaction to authentic flavors). I haven't had some of these flavors for years, and I was delighted. We also ordered the Chinese-influenced fried rice noodles recommended by our waiter - Penang Char Kueh Teow -- which included, in addition to the squid and Chinese sausage, shrimp and bean sprouts in a spice soy sauce. Everything was sensational.
As for the Hainanese chicken -- my experience of this dish, which I've actually only had in China, is that it's boring, not exotic. It's the perfect dish for someone with a cold (which is why I first ordered it). They probably warn diners away from it because they're worried people will complain about the food being uninteresting. Just a guess, but I can't imagine they would be worried about "authentic flavor" with this wholesome but bland dish.
I was delighted with my experience at Penang. Now that I've found it, I'll be back. (Nice decor, too.)