This question is in response to an answer given here
It is my understanding that ～ている in general is used to show that the state reached after the verb has been initiated is continuing. This manifests itself in English as the present progressive or the present perfect.
帰っている ⇒ I returned and am currently in the state of having returned.
歩いている ⇒ I started to walk and am currently in the state of walking.
Logically extending this understanding to ～ていた, I come up with it meaning that an action occurred in the past, it continued for a period, and then the state ended.
帰っていた ⇒ I returned, was in the state of having returned for a bit, and now I am no longer in that state.
歩いていた ⇒ I started to walk, continued for a bit, and then stopped.
Based on this understanding, I would have assumed that 死んでいた does not make sense as it would imply that the dead person is no longer in the state of being dead. However, the linked post includes 死んでいた (translated as "He was dead") as an example suggesting that it is perfectly acceptable. In English, stating "He was dead" really only makes sense if the discussion taking place is about the past. Therefore I reason as follows.
Consider the following
Are these conclusions correct. If not, would you please be kind enough to explain my errors?
This states that Person B became acquainted with Suzuki at some point in the past but is currently not acquainted with him.
This states that Person B became acquainted with Suzuki at some point in the past and does not make any implication about the current state of his acquaintance.
This states that Person B became acquainted with Suzuki at some point in the past and is still currently acquainted with him.