The answer is that I know my qualia are right because they make sense. Qualia are not pure "outputs": they feed back on the rest of the world. If I step outside on a scorching summer day, then I feel hot, and this unpleasant quale causes me to go back inside, and I am able to understand and articulate this cause and effect. If my qualia were actually those of a computer chip, then rather than feeling hot I would feel purple (or rather, some quale that no human language can describe), and if you asked me why I went back indoors even though I don't have any particular objection to purple and the weather is not nearly severe enough to pose any serious threat to my health, I wouldn't be able to answer you or in any way connect my qualia to my actions.

I'll grant that people actually have something in mind when they talk about "qualia", and the primary disagrement is whether it's epiphenomenal or fundamental.

Even still, this paragraph is extremely confused. The question seems to be "can qualia be simulated?" There's no reason to believe they cannot, whether or not they're an epiphenomenon.

"But a simulation of a thing is not the same as the real thing!" - a banal tautology. Say specifically what's different (in the relations between simulated things) and fix it.