Considering they invited it but didn't revolutionise the use and potential uses of gunpowder. Why didn't they develop it at the rate or standard of the European powers? Very stoned and would approached an answer by one of you fabulous people. I understand that their engineers were maybe just not on par but is their any other definitive reasons?
This is not the right question to ask. Lots of things don't happen in history all the time. The right question is what factors led to the adoption and evolution of gunpowder weapons in Europe, and then to ask if those factors were present in China. Even this way of thinking leaves you blind to other factors that could also have led to adoption and evolution of gunpowder weapons that may have been present in China.
Nevertheless, it took hundreds of years for gunpowder weapons to become the primary armament in European warfare. We have to see an initial use-case to explain its adoption while the technology is pretty crappy. We have that with the dominance of heavy cavalry in the late medieval age. Pikemen are a natural counter for that, but they are vulnerable to ranged troops. Adding some gunmen to the pikes creates a very versatile combined arms unit.
But why not archers or crossbowmen? Archers generally can't pierce mail (heavy cavalry and their horses are heavily armored). Crossbowmen seem like a reasonable alternative. Powerful bolts, good range. I don't know why guns were chosen over crossbows, but there is probably a good reason. Guns are a good compliment nevertheless because they have good range and good penetration.
Guns now have a foothold in the battlefield, and it so happens that the continued evolution of tactics continues to find a use for guns, so we continue to see improvements in gun technology, such as smaller anti-infantry field guns which are great against those massed infantry pike blocks, line infantry tactics which provide greater fire power and smaller targets, etc.
That's what happened in Europe, but why didn't this happen in China? I'm no expert on Chinese military history, but my understanding is that China didn't have the dominance of heavy cavalry we saw in the west. Their foes engaged in a lot of horse archery and they were also content with their use of crossbows. Someone please correct these likely mis-characterizations please.
So basically, gunpowder weapons filled a niche in European warfare that didn't exist in China, and it turned out in the long-term to be a useful technology to develop.