The help from Europe did not occur overnight, France entered in 1778; Spain in 1779 and the Dutch in 1781. It took the combined Allied navies to help fight the British at sea, and by 1782 the British were finally outnumbered enough to effect the war in favor of the Americans. This could have only happend by the efforts of keeping an American armed force in the field.
The Civil War was fought too fast and furious for the South to sustain itself long enough to find that ally willing to help. The question is would a European government back a guerrilla force over a regular military force?
The E.P. had an effect of energizing the Confederate effort, and negotiated peace almost impossible. I don't believe U.S.C.T. had that many combat casualities on the big battlefields.