is the wrong way. Such a layout can be easily done with your own list-command
\setuplabeltext[chapter=CHAPTER~]
% \define[3]\ChapterList % no label!
% {#1\crlf#2\wordright{#3}}
% \define[3]\ChapterList % fixed label, wrong for appendices!
% {\labeltext{chapter}#1\crlf#2\wordright{#3}}
\define[3]\ChapterList
{\currentlistsymbol\crlf#2\wordright{#3}}
\setuplist[chapter][label=yes,alternative=command,command=\ChapterList]
\starttext
\startfrontmatter
\completecontent
\stopfrontmatter
\startbodymatter
\chapter{Title of chapter}
\section{Title of section}
\stopbodymatter
\stoptext
Wolfgang