The extra synth is in there because Ingenuity is used, rather than Ingenuity II. This means you need a bit more progress to complete the synth, and it doesn't really matter how much or where it's done. I suppose it's done early because there's no reason NOT to do it early. You might think that spending 10 durability to save 8 CP isn't worth it, but in this case, it is. I tried modifying this macro to use Ingenuity II, and I couldn't get it to 100% without CP food. I wind up 1 CP short (I have 248 base), and I get 10 extra durability. So, this seemingly random CSII makes it work out nicely.