Modern Elmo the wing issue was fixed; the P-8 also had a wing issue resulting in a different wing.
AFAIK it was known about and was actually down to two different CAD systems not speaking the same language, one measuring the fuselage and one building the wings. At the time of the MRA4 contract a new build would have been ideal as a new production line could well have lead to orders from across the world including the US, 200 to 300ish MPA required within the next 20 years or so. I believe they reused the fuselages from MR2s hoping to secure the contract by making it sound like a modification to the Government, it was a poor decision then and became another mill stone round the neck of the project for various reasons since. The reason an Airbus airliner type wasn’t pursued at the time is because there would have to be too many compromises in performance and capability, the USN chose the 737 as it couldn’t afford a better solution. Rather than a P-8 competitor the MRA4 should have been new build, maybe the US would have shown interest and assisted in R&D and we would all have ended up with the best platform.