How to Transpose Elements

I am working with older documents that have invalid elements. I was hoping there might be a way to change them in bulk rather than manually editing each element. I have a conversion table of the invalid elements and their current elements for a translation but no real way to push these updates through the full doc. 

I know there is the scripting function in FrameMaker but since I've never coded in Java I'd be starting from scratch and would need help with that if anyone can point me in the right direction.