Did the Prophet (peace be upon him) separate the reservation of the answer from the meaning of response in the first hadith, then include it within the meaning of response in the second hadith, and did the scholars rush in judging the meaning of the answering of prayer?

There is no contradiction; rather, the flaw lies in the failure to distinguish between marfu' (attributable to the Prophet) and mawquf (attributable to a Companion) narrations. The first phrasing, narrated by Ibn Abd al-Barr, is mawquf to Zayd ibn Aslam. As for the authentic marfu' phrasings, some of them state: "Allah will grant him thereby one of three things," while others state: "His supplication will be answered; either it will be hastened for him in this world, or it will be stored up for him in the Hereafter, or it will expiate sins from him in proportion to what he supplicated." This clarifies that the answer will be one of the three mentioned.