Yes, Roger, you are correct. Coulouris, perhaps because he was married, had children, and was a British subject of Greek parentage, shied away from Welles' wildlly unsafe projects.
Coulouris appears to have thought Welles was a bit nuts, full of crazy ideas, but then, after CITIZEN KANE, he squandered his own good fortune on Broadway, trying to present Richard III as Adolph Hitler. Ian McKellan made the idea work, forty years later, but Coulouis could not.
He spent World War II, back in Hollywood, playing Nazis. He seems to have had less to do in America, following the War.
Eventually, he looked nostalgically back on his days on the British stage. He even appreciated the time he worked with his father, scavenging trash. He tells a story about the family firm receiving a consignment of cigarette papers soaked with sea water. He hit on the idea of spreading them out, one by one, on large furnace boilers to dry them out. He notes, however, that it was unlikely that many of them were ever resold.
Like his son, he settled into English country life, and while doing the odd character part, he brought up two successful children.
One could do worse.