Yeah, since the Narrator and Yularen are always listed as separate characters, I really doubt Yularen is narrating every episode of Clone Wars. Why would he? Is it during off-time is he telling those stories to clones in the mess hall or something?
"Our heroes crash land on a distant planet-"
"Why does the Admiral use that voice? It's kinda silly."
"I don't know, but I wouldn't question it. At least it's entertaining."
As for who I hear narrating the opening crawls, it's just my own voice. I've never had a certain character read the crawl in my head.