Example: I have countless Spaces and get 100's of updates in all the spaces.
With that said, so you click on say Space-35, read the comments/question but at the moment you are not aware of a response to provide, space is marked read
Then reading through other spaces you find a good response BUT the space name slips your mind and now you are trying to search on keywords or click countless spaces to find that Space.
I have seen this in other Apps and that there is a Back Button that remembers your Space hopping and you can use that to get back to the Space OR make the BackSpace button perform the same action if clicking in the View ALL space list.
The preferred option would be able to mark the space/comment for follow up and be able to jump back to your follow-ups but guess that is a maybe feature for the future...