From my understanding of the process. Using a pre-certified module reduces your risk, because the module on its own is compliant.
Therefore when you send your whole product for testing, there should not be any issues with the 2.4Ghz band emissions, or direct emissions from the nRF52 processor.
I noticed however with the product that was linked to, is that it can have an external antenna
"Chip antenna or IPEX MHF4 Connector"
If you connect an external antenna, you would invalidate most of the RF compliance
So its not a magic bullet.
I have developed hardware using WiFi and other BLE modules, and they have passed testing and been certified without any issues.
But a lot still depends on who whole system (schematic & PCB design), I recall one company who put a ground plane directly under the antenna of a module, which causes all sorts range and certification problems ;-)
Right, I've seen similar troubles on one project. So the consensus among "smart guys" is to have RF expertise or some external consultancy, work with custom PCB design including BLE part, tune specific antenna for each product version and certify it then one by one?;)
RF design is IMHO a black art, which is best left to the professionals, hence I dont touch it.
However Nordic provide reference designs at PCB level, which somewhat mitigate this problem.
I use another option, which is to contract a Chinese company who specialise in BLE and RF, to customise an exiting, tried and tested design, to add the functionality I require for a specific product.
The product still then needs to be tested and certified, but as the RF end of the PCB is the same as other boards which have passed certification, there is normally not an issue with getting the customised board certified
