Scientists discover things that I don't understand every day.
A sufficiently advanced discovery in, say, mathematics can only be understood by other mathematicians. Does that make it less of a discovery? So what's wrong if a machine discovers something that can only be analysed and proved by other machines?
The mathematicians understand the discovery, so what's the problem? With "AI", nobody understands it. If you ask, the AI may say it understands the results, but it is probably lying.