As-salam alaykum
To my knowledge hitherto, there is
no extant personally autographed copy of Imam Bukhari's work written with his own pen or arguably, any known surviving transcription of his actual work. This is arguably the case with the authors you have mentioned collectively whose works generally form what is known as the 'Sahihyan' canon (Bukhari & Muslim).
It has been long argued (and appreciated) within the ambit of scholarship that Imam Bukhari's work for example was transmitted through
various students and as some have argued, remained
'fluid' even generations after his death, with recensions.
Recent copies of Bukhari's work that are purchased in popular bookshops and remain in common dissemination are based on larger commentaries such as the
Fath al Bari by Ibn Hajar Asqalani
as late as the 15th century CE and other volumes, such as
Umdat al Qari by Badr al Ayni (also 15th century). There are many other commentaries besides these which are not contemporaneous to Imam Bukhari’s life. Any astute academic will be aware of the oft disagreements noted in these works.
My simple honest response would be,
only God knows best what Imam Bukhari
actually transcribed in his lifetime with his own pen and how far a variant today's understood copies are of his original work.
It is also worthy of note, ancient manuscripts that bear the name of Imam Bukhari's work, which are nothing but later renditions by copyists, at times in ornate calligraphy.
For an example of a scholarly appraisal, please see Appendix 11,
'The Question of the Attribution of the Sahihayn' by Jonathan A.C. Brown in his Book
"The Canonization of al-Bukhari and Muslim: The Formation and Function of the Sunni Hadith Canon"I have also provided a brief illustration below showing a very brief overview of transmission of Imam Bukhari’s work
[1]http://quransmessage.com/charts%20and%20illustrations/bukhari/bukhari%20FM2.htmI hope that helps, God willing.
REFERENCE:[1] IMAM BUKHARI - Important dates, events and canonisation development of the works of one of Islam's important Ahadith collectorshttp://quransmessage.com/charts%20and%20illustrations/bukhari/bukhari%20FM2.htm