Here is my MWE:
\documentclass[11pt,a4paper,oneside]{memoir}
\pagestyle{plain}
\usepackage[explicit]{titlesec}
\usepackage{fontspec}
\usepackage{xltxtra}
\usepackage{polyglossia}
\setmainfont[Mapping=tex-text]{Liberation Serif}
\setsansfont[Mapping=tex-text]{Liberation Sans}
\setmonofont[Mapping=tex-text]{Liberation Mono}
%% Ensure sequential numbering of subsubsections.
\setsecnumdepth{paragraph}
\counterwithout{paragraph}{subsubsection}
\counterwithout{subsubsection}{subsection}
\renewcommand{\thechapter}{\arabic{chapter}}
\renewcommand{\thesection}{\arabic{section}}
\renewcommand{\thesubsection}{\Roman{subsection}}
\renewcommand{\thesubsubsection}{\S\arabic{subsubsection}}
\setcounter{tocdepth}{3} % Must not precede the above
\titleformat{\paragraph}[hang]
{\raggedleft\normalfont\small\itshape\bfseries}{}{0pt}{#1
\arabic{paragraph}}
\usepackage{hyperref}
\begin{document}
\tableofcontents
\chapter*{}
\section*{Beauty}
\label{sec:beauty}
\addcontentsline{toc}{section}{\nameref{sec:beauty}}
\section*{Preface}
\label{sec:preface}
\addcontentsline{toc}{section}{\nameref{sec:preface}}
\chapter*{First Grade}
\label{ch:firstgrade}
\addcontentsline{toc}{chapter}{\nameref{ch:firstgrade}}
\section*{Introduction}
\label{sec:intro}
\addcontentsline{toc}{section}{\nameref{sec:intro}}
\section{Outline}
\subsubsection{Charlie}
\paragraph{Exercise}
\paragraph{Exercise}
\subsubsection{Delta}
\section{Start}
\subsubsection{Continue}
\chapter*{Second Grade}
\label{ch:secondgrade}
\addcontentsline{toc}{chapter}{\nameref{ch:secondgrade}}
\setcounter{section}{0}
\setcounter{subsubsection}{0}
\section{Declension}
\subsubsection{Echo}
\paragraph{Exercise}
\paragraph{Exercise}
\end{document}
The document structure is a bit unusual (it starts on section level, no first chapter specified, and subsubsection numbers run continuously through a chapter), but it is not for me to modify. There are two troubles:
(1) Echo ToC entry points to Charlie, and Declension to Outline (intuitive, but still wrong);
(2) Beauty, Preface, and Introduction ToC entries appear nameless and linkless, though First Grade and Second Grade chapter entries are OK.
Hope there's a way to put things to rights.
titlesecandmemoir?\paragraphtitle is customized with\titleformat, which requirestitlesecmemoircomes with its own facilities of making structure command format, no need to screw it up withtitlesec;-)