From https://tracker.moodle.org/browse/CONTRIB-5576?focusedCommentId=476138&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-476138

Questionnaire displays activity name without applying multi-language filter in the intro page (mod/questionnaire/view.php?id=) using Questionnaire version 2017050101.

Eg. like this:
<span lang="en" class="multilang">Satisfaction Questionnaire</span><span lang="de" class="multilang">Zufriedenheitsbogen</span><span lang="fr" class="multilang">Questionnaire de satisfaction</span>

I changed this on line 51 in view.php:
$questionnaire->page->add_to_page('questionnairename', clean_text($questionnaire->name));
to this:
$questionnaire->page->add_to_page('questionnairename', format_string($questionnaire->name));

So now I  am using format_string instead of clean_text and it works fine for me now.