The thing about the Expedition is it has ALWAYS been stated and known it was created from a screen used Raiders stunt jacket from the very beginning. It has never been said it was patterned from a 'hero' jacket. It is what it always HAS been.
It's about as 'authentic' in design as it gets. It's just not patterned after one of the 3 favorites of Spielberg that was used as a hero jacket.
The few changes that WERE made after the first production runs were done at the request of the fans.
FS/G&B found themselves in the same boat that Wings and Wested found themselves in. Fans claimed they saw this or that in fuzzy screen grabs (we didn't HAVE the fine equipment we have today for clear shots). In order to keep customers happy, slight changes were incorporated into the patterns, as that's what customers were telling them 'they saw'.
In FS/G&B's case, it made no difference that a screen used jacket had been actually handled, examined and measured to create the patterns. Folks wanted the changes THEY thought they saw on screen. The jacket companies were in the business to sell jackets and to KEEP said customers happy, so those changes were made. It didn't make any difference to them one way or the other.
For example, the position of the yoke was changed due to FAN demand, NOT due to a pattern change. As has been discovered, what fans were seeing were different jackets from shot to shot in the film (as commented on by others in the past in many discussions, but shouted down and rediculed at the time by the community), and the yoke was higher on one, and lower on another.
The irony in all this is (and this has been said by Wings for years) is that the inconsistancies in the current design of the manufacturers jackets is all due to requests/demands of the customers. Once those demands/requests were met, now they're being criticised by those same customers for MAKING those changes, and being accused of being the source OF the new perceived 'flaws' in the patterns.
The FS/G&B changes were slight, but they were not made using the old Keppler patterns.
Regards! Michaelson