An ISA spec says how a processor should behave. A processor either conforms to such a spec (behaves exactly like the spec says it should), or it doesn’t (behaves differently in some situations).
ISA has nothing to do with correctness of programs. If a processor conforms to its ISA spec then all programs will behave as they should behave according to the spec, both correct and incorrect programs. If a processor does not conform to the ISA spec then programs can behave different from how they should behave.
A spec cannot be wrong, by definition. It can be nonsensical (like if the spec says that an “add” instruction should subtract, but it’s never wrong.