I’m new on your api and start testing it.
However, my first test is not so good, as you can see on the picture, the api create an “optimized route” but on the map it seems not so well optimized 
Any thought ?
Indeed that does not seem to be optimized. It may be in the original order. Did you set the skipOptimisation parameter? If you did, remove it completely from your request.
If that does not help, we need the full request and result to check in more detail. You may share it here, or send it to info@routexl.com