I came up with this solution. It resizes the duration using a FunctionGenerator. Not sure if this is doing fancy interpolation like in the KymaSeven wave editor, but it works.
Make a folder of samples all the same duration.kym
Choose a sample file from the folder of samples you would like to batch, and the output will be automatically renamed with a "_batch" attached. The output files are written into Kyma 7 Folder/DiskTracks the default directory DiskRecorder normally saves to.
In the image, you can see the upper necklace is the folder as it was and the lower one the new result.
I am not sure if it is giving me exactly the right results, will look into it...