Keith you have a truly beautiful BLE,
Your gun's receiver is similar to a Christophe BLNE (not marked JB) and another BLE marked JB. Your gun's proof marks are similar to those on my Christophe SLE (to include the AD under the date stamp) and my Jules Bury marked(non branded DR)
As promised some pictures and notes on my Christophe Bury Double Rifles.
I note I am the worse photographer going and much of what I tried to capture is not that great.
The First Double Rifle is a 1926 best quality side-lock ejector 10,75x52 Springer Double Rifle. Game scene and Scroll coverage signed by noted Liege engraver Schoffeniels. Hidden 3rd fastener on a triple bite Purdy bolt system, articulated trigger, carved fences, grayed Holland and Holland bar action side-locks with gold plated lock parts, bushed firing pins. Stamped JB under crown for Jules Bury on action. It is marked Louis Christophe of Brussels on the bottom of the receiver
The Second Double Rifle is a BLNE 10,75x52 Double Rifle Grundig. It is engraved with 40% coverage Scroll and the engraving is unsigned. It is not stamped by the actual maker. It is marked Louis Christophe of Brussels on the bottom of the receiver. It was heavily used and I have since had the checkering recut and wood refinished.
The Third Double Rifle is a circa 1928 BLE chambered in 350 Griffin and Howe. It has 60% coverage scroll and the engraving is unsigned. Hidden 3rd fastener on a triple bite Purdy bolt system, articulated trigger. Stamped JB under crown for Jules Bury on action. It is not marked by a seller on the bottom of the receiver or rib.
Reference the identity of your gun's engraver. You gun's engraving is unquestionably good quality. I really can't say anything for sure if it is or not. Schoffeniels seems only to have signed his best work (I have four signed SLE best guns)
In emails with Schoffeniels grandson I saw examples of layouts for midgrade guns, so it is sure he did some, but I can't begin to speculate on how many. His grandson told me that his grandfather was a factory worker by day and engraved standing up in a garden shed in his backyard.
