Taking Mohammad's suggestion, I'm making a new thread with a clear description of one desired plugin for TW5 (to serve as a partial successor to RedirectMacro and other AutoLink type plugins for TW Classic). The easiest fix to implement, I imagine, is just an action assigned to a button as follows:
(1) Simple interface to confirm filter condition. By default the plugin displays a title list for non-system tiddlers without the excludeConnectify tag. User is warned to review the list to confirm that all of these strings should be converted into links *throughout* the set of tiddlers that meet the filter condition. (Looking at the list, user realizes there's a tiddler called "about" and fixes that fact, since it would probably be terrible if all instances of the word "about" became links to that tiddler. Maybe the tiddler should be revised to put "about" in the caption field, while the title is made more descriptive. Etc.)
(1a) Ideally, we also see a list of aliases (but not captions) that exist for those tiddlers that meet the filter condition. (If there are multiple alias plugins, perhaps this is harder. But if they all use a field called "aliases" maybe it doesn't matter?)
(1b) Allow more complex filter conditions? one could have more complex conditions, like an opt-in tag (require an includeConnectify tag), or some more complex Boolean condition (like non-system tiddlers that have the tag "definition" but not the tag "obsolete"). All this could be user-configurable, though first version could be simple.
(1c) Allow configuration of Case-specificity? Do you want to strings like Tiddler Name
and Tiddler name to become links to tiddler name? What about vice versa? (By default, instances of Philosophy in the text will become links to philosophy, but not vice versa. That way, author can capitalize a tiddler title, like Mill, exactly when it's a proper name, trusting it would not become accidentally become a link when tiddler text mentions chances to mill around with philosophers. )
(1d) Allow for an escape character where a particular instance of a string within tiddler text should not become a link, the way ~ prefix serves to keep an instance ~McBoatface from becoming a link. (Leave out of initial version? User can simply scan for likely trouble and keep marginal tiddlers out of the filter condition.)
(2) Connectify! button performs action: Executing the macro searches within the text of all tiddlers that meet the filter conditions, and replaces all instances of tiddler name with [[tiddler name]] links. It also replaces all instances of each alias string with [[alias string|tiddler name]] links.
For now, that would be a huge step toward recovering the functionality of RedirectMacro. The more ambitious variant of the plugin would also tweak the tiddler save process so that, if the tiddler's in the filter condition, potential links (to other filter-condition tiddler titles and aliases) within the tiddler's text would be converted into [[links]] during the save process. Then the user can occasionally "clean up" with the button action so that existing tiddler text can "notice" linking opportunities that have developed since the last use of the action.