In the meantime, Taiwan maintains traditional Chinese writing while using Mandarin for speech. Table for clarity:
Simplified + Mandarin -> Mainland China
Traditional + Cantonese -> Hong Kong, Macau
Traditional + Mandarin -> TaiwanIt's actually a many-to-one mapping - going from traditional to simplified loses information, and people have to resort to natural language processing algorithms (mainly n-grams) when going back the other way.
Also, many of the "simplifications" are based on Mandarin pronunciations, and were quite incomprehensible to me as a Cantonese speaker when I set foot into mainland China for the first time years ago.
Some of these proverbs are known in mainland China however. 隔墙有耳 for example is a Mandarin saying as well (though perhaps derived from original Cantonese?).
On another note, mainland China (including Canton) actually uses simplified Chinese writing (which came out from the Deng Xiao Ping era) whereas Hong Kong specifically maintians the traditional writing. The difference is literally less strokes and simplification of the characters. The infographic here uses the traditional writing. Personally I feel the two writings are mostly close enough that people should be able to guess what the other means. And AFAIK, it's a 1-to-1 mapping anyway.