Why don't they say the name if they know it? The Emperor is not on Teishu-san or Sage-san's side, I think, so I don't see why he'd care about keeping the name of the spy hidden.

There's also no risk of those two silencingthe Emperor -- or is there? Do you think they could if they wanted?

[It'd be a bit easier to deal with this all if things were clear instead of said through riddles, that's for sure]