We continued to do research and got annoyed by the need to promote inline math environment to equation/align/equation*/align* environment repeatedly, so we quickly wrote some elisp code. (lol, totally procedural programming in Lisp.) We also defined interactive functions based on this one, but they are not posted.
We have pointed out elsewhere that Emacs 25 on Windows hung when editing files containing non-ASCII characters. Thus we refrained from upgrading to Emacs 25. (Not completely sure if all non-ASCII characters are bad. Examples of bad characters: “(╯°□°)╯︵ ┻━┻” and “土雞”.) Now we need to upgrade. After googling somewhat we found