Setting the "replace" property to true in a sounds.json file will cause all other properties to be replaced, even if nothing is specified for a property

When editing sounds.json files, if the "replace" property is set to true, then the other properties, "subtitle" and "sounds", will be replaced even if nothing was specified for those properties. So if you didn't set anything for the "subtitle" property, then no subtitle will appear at all, because it will have been replaced by nothing. Likewise, if you didn't set anything for the "sounds" property, then no sound will play at all.