No, Congress doesn’t have the final say in the election

Rather, Trump’s argument is that certain state election results should not have been certified, and that the electors should not have voted in accordance with the certified results in their respective states. (Because of alleged irregularities in the voting process.)

But these objections do not concern errors in the counting of votes of the electors. They are, instead, a sweeping, substantive objection to the electoral process itself. For which the Twelfth Amendment provides no remedy.

So, unless you interpret “counting” to mean something far different from merely counting, then recognizing the kind of objections that Trump’s supporters are threatening would exceed the Constitution’s narrow grant of authority to Congress to “count” the votes.

Meaning: It would be unconstitutional.