My speculation is that many Pata were indeed fitted with European blades, but even more so were fitted with locally made Indian blades that sometimes imitated the European design.
The fighting style with the Pata involves ample circular movements (of the whole arm and body) that require particularly flexible blades. A Pata swordsman will practically spin around waving the blade in circular moves and create a wide perimeter around him where any opponent would be at risk of being struck. If the blade is not flexible enough, a shield or even a stick can not only block the blow, but can easily throw the wielder off-balance or even break his arm. Therefore, the blade must necessarily be very elastic so it can bounce off any rigid parrying device and dissipate the shock of the parry.
While some European blades may be elastic just about enough to provide some functionality to the Pata, most of them were way too rigid to be of practical use in a Pata mount.
And I particularly doubt that any European swordsmith would bother to produce dedicated Pata blades for export to India, since even in India Pata wasn't very widely used, and since India itself didn't see such a dramatic shortage of native capable swordsmiths.
I am attaching some photos of a Pata I have, where one can easily see how thin the blade is (last photo).
Also at the link below, you can see a Pata with a very similar, very thin and elastic blade.
http://www.vikingsword.com/vb/showthread.php?p=92078