Watcher/Addresser and Engineer/Reviewer ship pre-built, not as demos but as genuinely useful starting points worth copying and adjusting rather than building your own from a blank roles list.
Watcher/Addresser fits anything shaped like "notice something, then act on it" — feedback on a pull request, a support inbox, an external system worth polling. Walk through building one yourself in Build a Watcher / Addresser strategy.
Engineer/Reviewer fits anything shaped like "build something, then have it checked before it's final" — a second set of eyes with no stake in having written the first draft. See Set up an Engineer / Reviewer pipeline for the step-by-step version.
Forking either one is just copying it and adjusting the roles' instructions for your actual project — the underlying shape (who hands off to whom, who gets their own workspace) rarely needs to change.