Nothing major, just something I noted while working on a file.
If you use the fullwidth environment and the immediate text within that is a \paragraph{Paragraph Tile} ... then the output after running XeLaTeX gives a warning of : something's wrong, perhaps a missing \item.
If however you add a character/text before the paragraph, the output is fine.
Example that gives error:
\begin{fullwidth}
\paragraph{Paragraph 1} This is a paragraph of text.
\end{fullwidth}
Example that corrects issue:
\begin{fullwidth}
~%Empty space
\vspace{-\baselineskip}%To correct for the extra line before paragraph
\paragraph{Paragraph 1} This is a paragraph of text.
\end{fullwidth}