Slightly late to the party, but I had the same wish to sync tangled blocks with their external files.
For this I can recommend org-tanglesync
This package looks for a :tangle <filename> property in the header of an org file and compares the block content to it. A diff is performed in the background, and then the user is prompted to pull or reject the external changes.
I find that this is more intuitive than org-babel-detangle because it does not require the external file to have extra org-babel magic for it to work, i.e. it is the source file that tracks the external exported blocks and not the other way around.