The dominant factor in the growth of the company in question throughout the years has been its success in maintaining technical superiority in product design and manufacturing techniques.
译文：该公司多年来发展壮大的主要因素是一贯成功保持了产品设计和制造工艺上的优势。

The dominant factor in the growth of the company in question throughout the years has been its success in maintaining technical superiority in product design and manufacturing techniques.
译文：该公司多年来发展壮大的主要因素是一贯成功保持了产品设计和制造工艺上的优势。

改进译文：该公司这些年来不断发展的主要因素是，它在保持产品设计和制造工艺的技术优势上一直非常成功。