As far as I'm aware it shouldn't cause any problems for the auto start on the CT vacuums, but all the Festool tools in the recent lineups I'm familiar with have had "fancy" electronics for soft start, variable speed, etc. built in. Most ither high end German power tools I can think of also have the "fancy" electronics as well, except some of the newer Fein angle grinders, that are meant to be useable on DC current.
All the versions if the Porter Cable 557 biscuit joiner, both the older types with the PC made motor, and the newer type that uses a B&D/Dewalt made motor, use a simpler motor without the "fancy" electrical modules. I believe the Porter Cable 556 biscuit joiners also lacked the "fancy" electronics.
Another thing that may cause issues, is that European made North American spec, electrical cords seem to use slightly thinner plug prongs than those found on US made power tools. I haven't measured the thickness difference, but the plug ends on the EU cords seem to fit loser into sockets. This doesn't seem like it should be an issue related to your problem, but who knows.
As others hame mentioned also check to make sure the auto start switch is in the right place.