People say I’m guilty, he’s guilty etc but it’s unlikely to hear “they were found guilty” outside of jurisprudence, and to say that when referring to a judicial trial and then say you meant a lay term when the professional term exists is a bit lax.
I wouldn’t say “WiFi” in place of “internet” while referring to an IT problem for example.
It was found that he raped someone, he is guilty of rape, but a judge did not find him guilty of rape. Why do you insist so much on muddling the definitions of these things? It’s not good for democracy or the judicial process to use terms randomly and without definition.