Some ways I've seen multiple languages handled:
I've seen some people use a filter for translating content into multiple languages. https://moodle.org/plugins/filter_multilang2
I've also seen people use multiple activities and then using a restrict access plugin to control which activities are visible. https://moodle.org/plugins/availability_language?nonjscomment=1&comment_itemid=1184&comment_context=50&comment_component=local_plugins&comment_area=plugin_general&comment_page=1
I've also seen people use multiple courses, one for each language and then enrolling the users based on language.
I've also seen people use a combination of all three to get the experience they're looking for. In your case, I would say different courses or different activities for each language might be the cleanest way to handle it so that all the responses are in the same language.
I've seen some people use a filter for translating content into multiple languages. https://moodle.org/plugins/filter_multilang2
I've also seen people use multiple activities and then using a restrict access plugin to control which activities are visible. https://moodle.org/plugins/availability_language?nonjscomment=1&comment_itemid=1184&comment_context=50&comment_component=local_plugins&comment_area=plugin_general&comment_page=1
I've also seen people use multiple courses, one for each language and then enrolling the users based on language.
I've also seen people use a combination of all three to get the experience they're looking for. In your case, I would say different courses or different activities for each language might be the cleanest way to handle it so that all the responses are in the same language.