If you can, you may also consider to use the new UTF-8 support in WeBWorK. Using it, you can just write "René Descartes" in your UTF-8 encoded .pg file. There is no need for special commands anymore. Accents should render fine in HTML and in the LaTeX output. It is available in the following pull request:
Be warned that this is not yet part of WeBWorK 2.13. So use it at your own risk. We would appreciate your feedback.