There are two cases here. A sort by ‘Tags Order’ means the order of items you chose under the tag corresponding to the group. Remember that you can manually rearrange items inside a specific tag in the Tags perspective.
When you sort items by ‘Tag’ in a custom perspective, the sort order doesn’t follow the order of tags in the hierarchy, unfortunately. It performs a character-based sort using the full path of the tag in the hierarchy. In your example, the tags are in the order of appearance of the emoji in the whole emoji set. If you didn’t have emoji, you’d find that ‘Hot’ would be sorted before ‘Today’, regardless of the tag hierarchy, because of the alphanumeric order.
This is a long-standing behaviour in the app. I get around it by adding underscore prefixes on some of my tags to get the order I want. It’s a bit frustrating because it’s inelegant but I’ve come to live with it! I wrote about this in this thread: Perspective for several most important tags
