According to the script for this episode, the pronunciation for Caldos was "CALL-dose". 
According to the Star Trek: Star Charts, on the chart "United Federation of Planets I" and "United Federation of Planets II", the Caldos system was located in the Beta Quadrant. This system, also known as Beta Octanis, was a single star system. Primary was a Class A star with a magnitude of +5, which was the same brightness as Sol. Caldos II was listed as a member planet of the Federation in 2378.