Rose wasn’t present, but has no alibi due to only being with Pearl at the time - Pearl probably belonged to White, so she’s unable to say anything about White being the culprit.
Or possibly, Pearl was present and was forced to secrecy by White.
White had the authority to demand that the witnesses lie about who they saw. That would explain everyone else saying they saw Rose shatter Pink with the sword, when said sword is physically unable to damage gems.
So White strolls up, shatters Pink, and immediately demands that everyone present say it was Rose. Whether they obey out of self-preservation, fear for whatever else had been threatened, or due to White having some kind of mind control ability, I can’t say.
As for the witnesses themselves:
Eyeball saw the entire thing, but she clearly wasn’t Pink’s soldier so she cared little about Pink’s shattering. She’s obeying White because she’s a still-living Diamond - killing Rose is just a means to a higher place in the heirarchy.
I’m not aware of any other witnesses (barring the ones simply mentioned by Zircon), but if there are any, they aren’t in a position to say anything.
Jasper seems like she might be a witness, but she actually isn’t. Pink was shattered before Jasper was even finished cooking - “I’ve been fighting from the moment I broke free of the Earth’s crust!”
So, nobody resembling Rose even appeared at the scene, let alone shattered Pink. It was all just orchestrated by White.