How do I copy keywords “backwards?”

[Phil Fischer]

I added Keywords to many jpg files when I should have added them to their scanned source files (tifs). Is there an efficient way to copy them from the jpg versions to their tif “originals?” Except for their suffixes, they are identically named. Obviously the keywords assigned to any one jpg can be dragged to its tif version (or to any any other image file). But I have about nine thousand of them, each with its own set of keywords, and each with its own tif source file (with no keywords). Is there a way to automate this? Is there a way to tell the jpgs to transfer their metadata to other files with the same names (minus prefix) or to any other files?

I’m working in Bridge3 OSX, but will use any software that can do this efficiently. And I will learn whatever scripting is necessary if that’s what it takes.

[I have gone]

Yes that would make it easier to use as the user interface in CS6/CC is terrible.