Note to self - never buy a frame that has black bands edged with gold pinstriping.
Actually, that looks fantastic! Good work.
Would it help if you were able to insert a "balloon" into the tube and pressurize the interior of the tube? This would apply some outwad force and might force the buckled tube wall outward. it doesn't usually take much pressure to remove the buckle. Then you'd just have to roll out any crease that had occurred.
Do you think you repair weakened the tube (or the overall frame) in any significant way?