The steps you have taken are all correct and reducing the "cupertinoChunkDurationTarget" will lower the delay from the default which is around 30 seconds.
When looking in the logs you should be able to see the duration of the chunks created for Apple HLS. As you mentioned they should be 2 seconds depending on keyframe interval.
If you can increase the keyframe interval to be every 1 second the "cupertinoChunkDurationTarget" can be set to 1 second also which will further reduce the delay.
The log line should look something like this
Obviously with a duration equal to the keyframe interval if the "cupertinoChunkDurationTarget" is set to 1 second.
LiveStreamPacketizerCupertino.endChunkTS[live/_definst_/myStream_160p]: Add chunk: id:1 mode:TS[H264,MP3] a/v/k:102/200/8 duration:8000