The 3M2 can't have 268 Y seats after W was added if it had only 200 before. I'm guessing it's supposed to be 168.
764 and 763 are different birds.. All 764 have W seats now.. Only some 763. There's also issue that some 763 have bigger J cabins than other 763s.
Part of issue may be that DL doesn't offer W as a cabin domestically. Thus the plane seatmap can show the same 763 as having no W cabin on flight to say JFK from LAX, but having one on the same exact plane from JFK-Europe. Same applies for 332/333. Its true on 764/A339/350 however those have all been modified so there's no confusion if plane has W seats or not on it.