It's a surprise to me to hear that SS has only been trying to recreate BIR curries "exactly" for the past 10 years. I've been trying for well over 20!
I'm not sure I've had a "eureka!" moment either. More of "steady progression", I'd say.
I'm also sure that there are enough decent recipes, and enough information, on this forum for members to recreate decent/passable BIR curries at home.
However, I'm equally sure that there is still that missing "something" that differentiates the resultant curries, from those from a truly good BIR restaurant curry, in both taste and smell.......