I really think you're mistaken. 'bitcoind sendfrom' doesn't do what you think it does. It debits the specified account, but uses whichever unspent outputs in your wallet fit the spent amount best* no matter which address 'owns' them.
* for a particular and somewhat weird definition of 'best'
This is very much correct as I also had a lot of misunderstandings about what "accounts" were when I first started playing with bitcoind.
So just remember that when "sending" an
account != address and the purpose of
setaccount is really only for "receiving" (and probably should not be allowed for external addresses but unfortunately I think that that is how the labels are handled).