Yekke: I assume you haven’t got a copy on hand, so I just checked it.
(my understanding:) ‘Acharei’ introduces a turning point; hence, the fact that Yaakov was now ‘choleh’ means something had changed in his situation. What changed? Before, he was ‘approaching death’, but now he is a ‘Choleh’.
What’s the difference between the two? The letter ‘ches’ indicates movement that is impeded while the letter ‘ayin’ denotes unimpeded elevation (think ‘nun-ayin’ and ‘nun-ches’).
An ‘oleh’ ascends by his own power (“lifeless matter sinks; only the force of life elevates the living” p.847).
When something prevents a person from elevating himself, that person is a ‘choleh’. Yaakov had transitioned into this status.
Prior to this, Rav Hirsch explains the bowing back toward the head of the bed:
Yaakov was seated in the middle of the bed, Yosef was facing him at the foot of the bed, and Yaakov bowed toward the head of the bed (backward). “It was a devotional act of thanksgiving to G-d, Who had guided him throughout his life and had brought him to this goal” (of succeeding in doing the last thing he had to do on earth.) (“Just as Eliezer prostrated himself before G-d when he had accomplished his mission, so did Yaakov here.”)