If you have used Dialogflow's system entities for name recognition, you know that they are not very good yet when it comes to non-English names.
I saw a post related to this recently.
It looks like some people are not aware of an important feature of Dialogflow. You can actually extend a system entity - so you can use all the values it already has, plus the new values you wish it could handle (a very good example is first names).
Here is how you can do it: