Sentence:  All of this makes some sense in terms of using the windfall brownfield site to <WSD>retro-engineer</WSD> a more mixed use form of development, but it does show up the shortcomings of the previous approach and the difficulties of achieving the new constraint policy. 
Meaning of the word marked with <WSD> tags:  To revise or adapt (an existing item or process) in order to achieve a new purpose.