Did Cangnan people in Zhejiang immigrate from Fujian at that time?

That's not true. Some of them are from Fujian. Most of them are locals or Wenzhou people. Lingxi in Cangnan speaks Minnan dialect. The inverted bucket in Fengchi, my hometown, came from Fujian, probably during the Daoguang period, and the ancestral temple is here. I heard that my ancestral home is in Quanzhou, Fujian. Cangnan Mazhan and other places also came from Jinhua and Yiwu, because there were pirates here before. So there are eight dialects in Cangnan, Wenzhou dialect, Yong dialect, Minnan dialect, Yiwu dialect and so on. There are many sources anyway.