No there isn’t, unless the OC specifically sets a limit by resolving at the AGM. For example, you can resolve that the EC can only approve building works up to an amount of $20,000, or can only engage a consultant up to costs of $X. Or you can set a more general limit, so the EC can only approve expenditure up to $Y, otherwise it has to go to the OC.
I am an EC member, and I would be reluctant to approve anything major without going to the owners. When we did a major building project, we had that approved at an AGM. There were variations to the project, and these were approved by the EC. One amount was about $40,000 but I wasn’t concerned about that, because the project couldn’t continue unless we did it.
However, the EC is accountable to the owners. If they went that much over budget, then at the next AGM, they should be asked why, and perhaps someone could put in an agenda item to limit their expenditure. Consultant fees wouldn’t be an enormous amount, how much was it?