On the big ice, its a lot easier to contribute without being a great skater because there is so much time and space. But in the NHL, It's incredibly hard to be an offensive player without being a very very good skater, especially for undersized guys. Marcus Johansson was an excellent skater in comparison to Cervenka, which is why he was a more effective NHLer.
Cervenka probably had offers to be a full time NHLer at multiple points of his career, but he'd likely have to slot in as a middle 6 scoring winger / PP specialist who struggles at 5v5. He was the type of guy who probably would have put up decent numbers on basement teams, but he's not the type of player contending teams would be looking to acquire.
He's like a Frank Vatrano or Daniel Sprong, or a poor man's Mikael Granlund.
He probably preferred to be a star overseas than a journeyman in the NHL. It's a much less stressful life. He still earned millions of dollars in his career, so its not like he was hard up for cash.