Dear Mr. Batenburg,
Thank you for posting your request on History Hub!
If you have not already done so, we suggest you contact the Library and Archives of Canada, 395 Wellington Street, Ottawa, ON K1A 0N4, Canada. We searched their online database Service Files of the Second World War - War Dead, 1939-1947 and located entries for Cyril John Jones, John Buckmaster, and Leslie Wallace Harvey of the Royal Canadian Air Force. Please see their webpage How to obtain copies or consult a file for more information.
In addition, if you have not already done so, we suggest that you contact the The National Archives of the United Kingdom, Kew, Richmond, Surrey, TW9 4DU, United Kingdom regarding their collections of combat reports and records concerning bombing missions in Europe as well as the series Air Ministry: P4 (Cas) Files relating to casualties suffered during air operations and aircraft accidents 1939-1945 (AIR 81). Regarding the Royal Air Force servicemen aboard PA-995, according to the The National Archives of the United Kingdom research guide “How to look for records of the Second World War” service records of British military personnel who served during the Second World War and later are still held by the British Ministry of Defence. Visit the Get a copy of military service records website for further information.
We hope this is helpful. Best of luck with your research!