Authencity Of Sahih Bukhari
No blanket statement can be given w.r.t any such book other than Quran regarding its 100% authenticity. Hadith science has many dimensions to it, ranging from how it was gathered, the health criteria w.r.t chain of narrators and w.r.t the content of the Hadith itself in addition to it being in line with Quran and Sunnah. Following points might help you understand a bit about the Hadith Science: Discussion 32850 • Reply 32869 To understand Hadith as a Source of Islamic Epistemology, please see: Discussion 21789 • Reply 21983 (although the whole thread is helpful) To understand the Hadith Compilation and Collection, please see: Discussion 50996 In furture, please post relevant Hadith references whenever you ask a question, it helps us in sorting of questions and replying to them accordingly. As far as narration on age of Aisha (rta) is concerned, that narration has been critiqued in the light of arguments mentioned in the following video: ( for other examples that you mentioned, please provide their appropriate references ) https://youtu.be/-LAS1PuQE7k