Is it correct to say that Allah Ta'ala is established over/on the Throne?

Answer

It is correct to say that Allah Ta'ala is 'established' over the Throne without assigning any interpretation to it. In fact, this is the best way. Allah's Istiwa is bila-kayf. It is beyond our understanding. We believe in His Istiwa alal Arsh without assigning any meaning/interpretation to it. He Alone knows its meaning.