It would be a really simple task to clear up the inconsistency issues between the YIJC, Films and Bantam novels. Just some suggestions to start:
-Peril at Delphi: Amend Indy's graduation date from Chicago in the book to June 1922; Have him start going to Sorbonne in the Fall of 1922.
-Fix dates after that to fit his new start date at Sorbonne.
-Amend the part in Peril at Delphi that he prefers skiing to baseball.
-Get rid of the marriage to Deidre since Lucas likely doesn't consider it canon. He could be ''with'' Deidre, just not married.
-Perhaps add references to Indy's war/spying service. Make it clear he served in the war; a token sentence or two on the subject is all that's required here.
-Have Indy or one of the Bantam novels mention Abner and/or Oxley offhand. Perhaps have Indy and Jack Shannon offhandedly mention Oxley and his obsession with Crystal Skulls; or amend McCoy's novels dealing with the Crystal Skull of Corzan to mention that an old pal of Indy's from college named Harold Oxley was obsessed with Crystal Skulls.
-Maybe amend Indy's and Deirdre's relationship and her death to late 1925-January 1926. If Deidre dies in January 1926, this allows for Indy to romance Marion later the same year (perhaps Fall 1926) while searching for the Staff of Ra. It gives him nearly all of 1926 for the Marion romance to happen.
-Change his interaction with Al Capone in 1927 so he and Capone recognize each other since they met in 1920 in the YIJC.
-Alter Indiana Jones and the Dinosaur Eggs to fit with the Temple of Doom sourcebook statement that he and Wu Human first met in 1914. Perhaps this is an inconsistency and they don't remember meeting then, though.
-Alter Indiana Jones and the Emperor's Tomb to make it seem as though Indy and Wu Han know each other already; Emperor's Tomb as it stands has them meeting just before the events of ToD.
-Alter Indiana Jones and the Philosopher's Stone to mention that Belloq and Indy's first meeting was in 1922 in Iraq, not 1933.
-Change Honduras to British Honduras in 1933 (though this really isn't a major deal since we're never told WHICH Honduras Indy is accused of being a graverobber in in Temple of Doom)
-Fix the date of his "vision quest" to 1913 instead of 1919.
-Change Crystal Skull in McCoy novels to "Cursed Skull" or something, since according to Lucas, Indy never saw a crystal skull outside of one in the British Museum before 1957.
-Fix Indiana Jones and the White Witch's description of Indy as a professor of Medieval literature to make him a professor of Archaeology. It's a simple one word fix that clears up an inconsistency.
-Perhaps change Indy's courses at Sorbonne to be Archaeology rather than Linguistics. He could minor in Archaeology while in Chicago and major in Linguistics there, and major in Archaeology at Sorbonne. While we're told he studied under Ravenwood in Chicago, he's not mentioned as being Indy's only teacher there, or his only teacher of archaeology.
Really, the Bantam novels only conflict with other EU materials and the YIJC mostly, and KOTCS to a small degree. The main grey area is MacGregor's early Indy novels. However as far as I'm aware, none of the Bantam books conflict with the original trilogy at all.
