All backmatter are root level chapters

main.tex

@@ -58,11 +58,11 @@
 %\importchapter{4-conclusion}{résumé}
 
 \backmatter
+\bookmarksetup{startatroot}% End the parts in TOC to set chapters at the root level
 \importchapter{5-back}{bibliography}
 \importchapter{5-back}{acronyms}
 \importchapter{5-back}{figures}
 \importchapter{5-back}{tables}
-\bookmarksetup{startatroot}% End the parts in TOC to set chapters at the root level
 \import{5-back}{backcover}
 
 \end{document}