[snip] According to historian David Hackett Fischer, about 23 percent of the Hessians who survived the war remained in America. Other estimates go as high as 40 percent. A significant portion returned to America after the war with their families. [/snip]
What Happened to the Captured Hessians?
https://www.washingtoncrossingpark.org/captured-hessians/
There was a Hessian prison camp out around Reading, Pennsylvania. Probably most of those men never saw home again. I don’t know if they were eligible to be formally exchanged for colonial prisoners.