BLE chip antenna matching
This calls for quite a specific and expensive piece of equipment, the VNA, as already commented. However, for a start you could start to design correctly the board.
First of all the .4mm trace width is bogus, because it depends on the kind of substrate and board thickness. It is correct for a 1.6mm FR4 double side board, however, probably that was the intention of the manufacturer.
You need to have the shortest track possible, with the matching components as directed in the reference layout and ground both under the trace and at the sides at a specified distance. This makes a stripline and the distance from the ground and the trace (on the three sides) determines the impedance.
The formulas are quite horrible, sincerely. Usually they put them in the modules instruction, I got mine from the proteus iii reference manual (a BLE module), there are about 3 pages on how to do that connection.
When you have done most probably it will be working altough maybe not at maximum efficiency. With a VNA it will be possible to tune the matching component to the effective layout (the VNA technician knows the detail).