Welcome to my world. Now you know how I felt converting D4D.

Also a 1:1 conversion is impossible I'm afraid. You might be able to get away with something that encapsulates properties and what not into having "" around the value, but with the inclusion of the Default { } block, and the fact people could include vars at any location in DECORATE, I don't see that happening. And that's just one reason... There's plenty more.
Want some advice for making things easier?
Replace the replaceable first. Use keywords to help you out. 'Whole word' options are a wonderful thing at some points. I.e. when searching for x, y and z to turn into pos.x etc.