I"m well aware of the difference. But can demigods even be saints?
I guess. People call him "Saint pelinal," and either way demigod or not he killed those Ayleid bastards! That's good enough for me.
Or unholy. Martyrs, and those within the cult who keep the commands are likely candidates for sainthood.
As far as Pelinal goes, he was Shor incarnate, so he was loftier than a champion. The most recent Champion of Cyrodiil (assuming he was made the Paladin of the 9 divines) would be the incarnate(?) of Pelinal, so he would be more on the level of immortal hero or at least a saint.
I could see the CoC being sainted, especially after ressurecting the knights of the Nine and being ressurected himself. Even if he was a "nameless" saint or simply Shezzarine, he's got the qualigfications as far as heroism and devotion go.
(LN is suddenly smothered by moths for calling him the shezzarine)