'has accumulated into' is correct and usable in written English.
It is typically used to describe how something has grown or been built up over a period of time. For example, "The company's profits have accumulated into a large financial reserve."
All my unprocessed anger towards other people has accumulated into one bristling ball.
Introduction: Diabetes has dictated many lives, and its lifetime treatment has accumulated into one of the most costly medical conditions, and yet, its pathophysicology is still undisclosed.
The government has been paying interest to the Bank of England for those loans, which has accumulated into a big pot of cash.
The black hole's gravity has gathered lots of gas and dust, which has accumulated into a disc that's spiralling into the hole – circling the drain, so to speak.
Some of that sand has accumulated into lovely dunes that can tell us something about wind patterns in these canyons.
"Persistent images of starving children and men with guns have accumulated into our narrative of the continent".
Candles, flowers, balloons, and stuffed animals had accumulated into a makeshift shrine on the lawn and steps nearby.
Nixon has taken a photo of the Brown sisters every year since, and the images have accumulated into one of photography's most affecting bodies of work.
Both carried the prizes they had accumulated into the final round, but once there, they also each drew a cash prize.
They have evolved, and over time these small changes have accumulated into huge changes and represent the transformation of a group of mostly large, Earth-bound carnivores into a plethora of flying birds.
Some analysts say even its decline matters far less than it might once have, because it failed, when times were still good, to convert some of the immense wealth it had accumulated into more lasting power and influence.
