nrf52 and Chip antenna Layout Questions
From the chip antenna datasheet:

https://www.johansontechnology.com/datasheets/antennas/2450AT18B100.pdf

It looks like you wire up a 50 ohm transmission line to the chip, then void the copper ground and power planes underneath the chip per their instructions.  This isn't too bad of a layout, and using the chip antenna prevents you from having to do a more precise antenna on the board.  These are usually a bad idea, because the constraints for your board get tougher, and would probably require a few design iterations to get right in addition to expensive test equipment to characterize.  So you're on a good path.

The thing to remember when designing controlled impedance is to get the specs on trace width and layer stackup from the board vendor you're going to use.  They will help you define those things on your layer stackup diagram, and also the trace widths for different controlled impedances.  Don't trust your own software; always go with the board manufacturer.  

In my experience, the shorter you can keep your transmission lines, the better.  In your image above, why not  decrease the distance from C23 to L1?  Minimize this; try to have as short a launch into your chip antenna as possible.  Keep the matching network components - it seemed like it had better performance in the datasheet.