If you want to treat the order of non-practice blocks (wordmemory to wordmemory3) as a between-subjects factor, then yes, that would be the way to do it.
If you merely want to randomize the order (not treating it as a systematic between-subjects manipulation), then you would simply make do with a single <expt> element:
/ postinstructions = (end)
/ onexptend = [values.completed = 1]
/ blocks = [1 = wordmemory0; 2-4 = noreplace(wordmemory, wordmemory2, wordmemory3)