We have an unreliable narrator
The account in Jayce's bio of his confrontation with Viktor is quite different from Viktor's own. In the former, he came in peacefully and tried to talk Viktor down. In the latter, he came in smashing stuff and Viktor ordered the automita to kill him to prevent him from destroying the lab (and the lives said lab was saving).
Now, on the surface that might not seem like a big deal. Sure, okay, it's just the two sides of the story, right?
Nope.
They say truth is a three-edged sword. Their side, your side, and the truth. We had the opposing sides given, but not the truth. We have an unreliable narrator, a biased observer. We can't take the narration we find in these two bios as wholly accurate.
And beyond that, it may be that we can't take the narration in any of the bios as wholly true. In much the same fashion, these are just someone's story. Someone's take on what happened. What someone wants to believe. Jinx' bio goes out of its way to describe how harmless Jinx is to everything except the pride and pocketbooks of Piltover. Perhaps, as with Jayce and Victor, this is just her side of the story? Or maybe the side of those who look up to her? People idolized Robin Hood after all, despite the guy just being a brigand.
What about Mundo's bio? It seems absolutely abhorrent that the medical staff of a mental institution would visit such torments on someone. Could it be, perhaps, that what we read was merely Mundo's misunderstanding of the purpose behind well-meaning medical attempts that have little if anything to do with face-eating mites? It would make for a salient mirror of Mundo's own well-meaning medical attempts on others.
If this is what's going on, that adds a whole new layer to League's Lore.
And one that I whole-heartedly welcome. Because a bio that's biased in the favor of the champ it's about? That gives you a very personal look into how they see themselves.