People say that you can exchange the /wait 1 second command
for "/stopcasting" command.
/stopcasting works after you put /cast<instant spell> and removes a (kind of bug) that prevents your macro to cast the next spell.
So, just try
/cast <instant spell>
/stopcasting
/cast <next instant spell>
/stopcasting
... and so on

Thanks, I'll have to try it out when I get home tonight