Technical Engineers and Marketing
Question: "Can technical engineers who had many years in development become good product marketers?"
Formally training engineers on a range of marketing practices can indeed lead to "cold, raw fish (AKA Sushi)" situations - a technical mindset in marketing to describe the product. The key is to have the training teach the necessary marketing techniques but also gently help the audience to transition from product-think to market-think.
Engineers can be good marketers but only if they evolve from a purely product-oriented technical mindset into a market-oriented business mindset. Very carefully designed training can accomplish that.