I've been working with Lucas S. on this in a WRC case. We believe that the source of the issue has to do with the encoding of the file, as compared to the file's contents and the encoding of the Eclipse workspace/Atelier Project/file in Atelier.
Copying this problem file into an Eclipse-only (non-Atelier) project does result in display issues until the file's encoding is changed within Eclipse. To change a file's encoding you can right-click the file in the Atelier or Project Explorer, click Properties and change the "Text file encoding" settings under the Resource section.
While there are workarounds*, you should be allowed to import these files into an Atelier project. The Atelier development team is reviewing this.
*Workarounds we've found in our investigation:
- Run an iconv command on the file on disk to change its encoding
- Change accented characters to their corresponding HTML entities, https://developer.mozilla.org/en-US/docs/Glossary/Entity
- Manually copy the HTML file from the CSP physical files directory into the Atelier project directory on disk, then change the file's encoding within Eclipse to avoid display issues