oh anyone know why Clark Steel has been called "Still" since KOFXII? Wasn't it originally Steel?
Generally, it's said that it changed because Clark Steel was too close to "Clark Kent, the Man of Steel".
I'm not sure if DC ever commented / saught action on it, but I do remember people complaining about the name being changed, and being suprised anyone would notice a little company like SNKP making such a semi-sly joke / tribute.
As far as I know, the "they changed the name to avoid legal repercussions" idea is just a fan theory. SNK has never said anything to explain it. Also, the katakana used for his name has never changed, only its spelling in the English versions. (It's always been sutiru.)
If you consider all the Superman references / jokes / parodies all over the world, it's very, VERY hard to imagine DC being bothered by a single allusion in a somewhat obscure game. Legally, they wouldn't even have a case. It's also very hard to imagine SNK being that paranoid about copyright infringement, when you look at some of their other character designs (Benimaru, K9999, Duolon . . .).
So, while it's not an interesting explanation, I think it's all just a mistranslation that started around 2004. No one ever noticed it, so it just kept being used. If you asked SNKP about it, they'd likely have no idea what you were talking about.