When should one use the past perfect? ("war... ge-[verb]t/en") I understand that the simple past is (roughly) for stories and the present perfect is (roughly) for the typical-past tense. (Feel free to correct me if either of these sound wrong.) Any help you could provide on this front would be much appreciated.
The tense Plusquamperfekt is for the tense Präteritum what the tense Perfekt is for the tense Präsens.
You have to understand Präteritum isn't related to the past at all ¹). It's related to a time a story plays in. Which is often the past, but it may be also the future or "fantasy time" in an alternate reality. You can also see Präteritum in this Erzählzeit describes present and future events, as Präsens does it for reality.
Das Planet-Express-Raumschiff hob kurz ab und stürzte dann zurück in den Hangar.
Später stellte sich heraus, dass Bender die L-Einheit verbogen hatte.
¹) if not used as a replacement for Perfekt with some common verbs.