There may be a way around it, but might not be high on the list. If you have specific post that matters to you, you could edit and add in an emoji that makes sense.Just noticing that not only are the old emoticons not available for new posts, but the old posts no longer have any of those emoticons showing either. They were various puctuation/text snippets that were interpreted by the prior software into displaying the right icon.
Not that there is likely much that could be done to alter that on the old posts. Makes for interesting reading at points to see the random text info.