A qualified translator does the translation.

The scientific editor / business editor verifies the translation accuracy.

The style editor (a native speaker of the target language, when needed) guarantees correct emphasis, logic, readability, and improves the style.

The proofreader corrects any remaining errors in spelling and punctuation, and improves the formatting of the text.

The project manager (editor-in-chief) supervises the text quality and discusses questions with the client as they arise.