This change in lexer_cpp.xml:
<Style name="Comment (normal)"
index="1,23"
fg="160,160,160"/>
is causing problems. When i changed it back to the previous form:
<Style name="Comment (normal)"
index="1"
fg="160,160,160"/>
the highlighter works correctly. The added ",23" part borks the highlighter and causes it to select colors from wrong entries.