Wrong.
If umpires were the judge then match referee wouldn't have to get involved. It's the referee who has the ultimate authority to take action against an act in a Cricket game. The umpires only have authority to make limited decisions within the ground. But that too they can abuse or misjudge.
Umpire's word is not an evidence. A judge word is not an evidence.
An umpire's decision is the result of their observation, not the evidence itself. The evidence is what happened (the ball hitting something). An umpire can make an error.
In a court, evidence is defined as testimony, documents, or physical objects produced for the inspection of the court. A judge's opinion or statement is not evidence; it is a ruling on the evidence.