For what it's worth, regardless of what is shown in writing, the way they actually pronounce his name in the show is Stark. In Japanese, the word stalk almost sounds like it's spoken with an O, like "stolk." I don't remember what episode it is, but in one of these past episodes they actually use the word "stalker" and it isn't pronounced the same way they pronounce Stark's name. They say his name more like "stahk" and the difference is pretty noticeable when you hear it. I suspect the whole thing with the card saying Stalk is another Gord Drive situation and it's just another translation error. I know a lot of people prefer Stalk but based on the in-show pronunciation, I think Stark is actually correct.

but,..Stalk actually makes sense. "Stark",...really doesn't.

I dare anyone to watch the scene with Misora and her pops with this going in the background and not cry:

https://www.youtube.com/watch?v=X--AnVFXeHU