stupid-questions:
An interesting solution! My true goal is to use software serial to print finalfreq to another Arduino, then eventually print it to a connected to the other Arduino. Could I do that with this array system?
Classic example of asking something while the question to solve is something else
Just do
Serial.print(freq1); // or Serial.write() depending if you need ASCII or binary out
Serial.print(freq2);
Serial.print(freq3);
Serial.print(freq4);
You don't really need to concatenate them (although yes an array would work)