From the lates CVS...
The ": " does not appear in all language files... for my particular system it must be using: en (not en_utf8)
[root@www lang]# find -type f -exec grep -H -i missingquestion {} \;
./de_utf8/questionnaire.php:$string['missingquestions'] = 'Folgende Fragen mss en noch beantwortet werden.';
./pt_br/questionnaire.php:$string['missingquestions'] = 'Estão faltando as seguintes perguntas ';
./pt/questionnaire.php:$string['missingquestions'] = 'No respondeu s seguintes questes obrigatrias';
./de/questionnaire.php:$string['missingquestions'] = 'Folgende Fragen mssen noch beantwortet werden.';
./es_utf8/questionnaire.php:$string['missingquestion'] = 'No ha respondido a la pregunta obligatoria siguiente: ';
./es_utf8/questionnaire.php:$string['missingquestions'] = 'No ha respondido a la s preguntas obligatorias sigueintes: ';
./nl/questionnaire.php:$string['missingquestions'] = 'Volgende vereiste vragen m oet je nog beantwoorden';
./pt_br_utf8/questionnaire.php:$string['missingquestions'] = 'Estão faltando as seguintes perguntas ';
./nl_utf8/questionnaire.php:$string['missingquestions'] = 'Volgende vereiste vragen moet je nog beantwoorden';
./en/questionnaire.php:$string['missingquestions'] = 'You are missing the following required questions';
./pt_utf8/questionnaire.php:$string['missingquestions'] = 'No respondeu s seguintes questes obrigatrias';
./fr_ca_utf8/questionnaire.php:$string['missingquestions'] = 'You are missing the following required questions';
./en_utf8/questionnaire.php:$string['missingquestion'] = 'You are missing required question: ';
./en_utf8/questionnaire.php:$string['missingquestions'] = 'You are missing required question(s): ';
./fr_utf8/questionnaire.php:$string['missingquestion'] = 'Vous n\'avez pas rpondu la question obligatoire suivante : ';
./fr_utf8/questionnaire.php:$string['missingquestions'] = 'Vous n\'avez pas rpondu aux questions obligatoires suivantes : ';
./es/questionnaire.php:$string['missingquestions'] = 'Le falta completar las siguientes preguntas requisitas';