Forest remain rooted to the bottom of the Championship table and are now without a win in nine games.
It was another frustrating afternoon for their fans, some of whom barracked Calderwood after his 76th minute substitution of Paul Anderson, who had been the their best player.
Forest went behind three minutes after half-time when Fitz Hall's long throw was headed on by Damien Delaney and Balanta's volley went in off the underside of the bar.
Both goalkeepers had produced good saves during an even first half.
Delaney whipped an early cross towards Dexter Blackstock, whose close-range effort was pushed away by Forest keeper Paul Smith.
And at the other end, Rangers' Radek Cerny dived to his left to keep out Chris Cohen's looping header.
Buzsaky almost put the home side ahead with a moment of brilliance on 24 minutes.
The Hungarian's chest-down and volley surprised Smith, who fumbled the shot but was able to gather the ball at the second attempt.
But Smith could do nothing to prevent Balanta's opener - or indeed Buzsaky's sizzling left-footed strike on the hour-mark.
Again a Hall throw proved to be Forest's undoing. This time the defender's delivery from the right was cleared only as far as Buzsaky, who fired home from the edge of the penalty area.
Buzsaky sent another cracking shot inches over, before Cerny tipped away Nathan Tyson's 25-yard drive.
Lewis McGugan pulled a goal back with a brilliant 30-yard free-kick, meaning QPR had to endure a nervy final seven minutes before securing their first win in five league matches.