Originally Posted by GUWonder

While the FCT use by the OP and OP's wife is highly unlikely to be disrupted by the current Schengen controls situation, the increased border checks are not limited to just surface transport crossings nor are they limited to just Austria-Germany trips. Flights into Germany from Croatia and Serbia have been getting more of an official "reception" at German airports too. And flights from VIE and even AMS have been getting more of a "reception".

The transit allowance and/or admissibility allowance of Serbian citizens into Germany for US-bound travels remains basically under the same conditions today as at this point last year.