When I setup a RAIL Radio Configuration I can set the Sync Word (actually two of them). But is there also a way to set the Sync Word later on at runtime as well?
You can reconfigure the radio any time in idle state. You should generate the new config ( the "generated array in rail_config.c) with different syncword in a separate project, and copy and use the new config in your original project.
With the syncword set to 32 bit and the requirement to let the user specify the "wireless address" this means I have to generate 2^32 configurations of 512 bytes each and store them somewhere in the flash of the FlexGecko. I hope you understand this is not going to work for me.
If you diff two config arrays, you will see you don't have to store the whole array.
A hint: you can also load partial configs, just keep full lines and the 0xFFFFFFFFUL, at the end.