Hello,
You can navigate through tags on the left side of the browser screen — there you can see the tags in a hierarchical way. You don’t actually need to look for tags in the “Tag box” of the card.
You can just click the tag, and all the cards that are in that tag will be displayed in the browser. From there, you can unsuspend the cards. Look at this example where I am looking for a tag and unsuspending the cards that are in it:
This tutorial can be helpful: Selecting/Unsuspending Cards by Tag
Let me know if this answers your question!