I'm afraid that there is no public transpor to Wuxi from Shanghai Airport after 20:00. And, it will also be urgent to catch a train. Please consider staying one night in Shanghai. Then, on the next day, you could catch an express train at shanghai Railway station or Shanghai Hongqiao Railway Station to arrive in Wuxi in one hour.

From Wuxi to Pudong Airport, it is suggested that you take an express train around 15:00 or 16:00 leaving for Shanghai. Then, from Hongqiao Train Station, please take the metro Line 2 to Pudong Airport. From Shanghai Train Station, please catch the shuttle bus Line 5 to Pudong.