The DEA hired a TSA employee to tell them which passengers had cash in their luggage.

No, at the federal level at least you are correct. In general civil forfeiture proceedings the government has 60 days to file the action. And I note that in Texas at least there is apparently a mechanism for forfeiture challengers to obtain their attorney’s fees.

The gravamen of a criminal penalty is that it is punitive in nature: it punishes prohibited conduct.

A civil action is remedial – it seeks merely to remedy a harm, not punish.

The differing standards of proof associated with these two goals can be traced at least back to the late 1700s. But it’s worth a reminder that the words “beyond a reasonable doubt” do not appear in the Constitution and are a gift of the common law.