When looking at the activities/resources linked to a tag, multilang content is not applied, so you see the whole string of multiple languages.

Steps to re-produce:

• Make sure multilang filter is enabled
• Go to a course
• Add a label
• Edit the HTML in the editor and add the following as the label HTML:
  • <span lang="en" class="multilang">English Content</span><span lang="nl" class="multilang">Dutch Content</span>
• Add the tag "test" to the label and save
• Go to moodlesite/tag/index.php
• Search for your "test" tag or click on it if it's there already
• Under "Activities and Resources" you should see your label, without the multilang applied: "English ContentDutch Content"