Mixed structure with int and string
There must be something wrong with the simulator you're using, because your code works for me (Arduino IDE 1.8.9, OSX, Arduino Uno).

struct commands
{
  int   cmd;
  char  descr[25];
};

commands cmds[] =
{
  {16, "Hammond Organ"},
  {17, "Percussive Organ"},
  {18, "Rock Organ"},
  { 0, "" }                   // end of list marker 
};

void setup(){
  Serial.begin(9600);
  Serial.write(cmds[1].descr);
}

void loop(){}