Using HERE Public Transit API V3 for searching stations with name and radius, I get up to 25 stations with the following query:
https://transit.ls.hereapi.com/v3/stations/by_name.json?
center=50.7374,7.0982&name=berlin&max=25&radius=90000000&apiKey={YOUR_API_KEY}
Converting the same query to HERE Public Transit API V8(next line) does not deliver any stations.
https://transit.hereapi.com/v8/stations?
in=50.7374,7.0982&name=berlin&r=90000000&maxPlaces=25&apiKey={YOUR_API_KEY}
In the migration document, there is no information regarding this matter. It is only mentioned that some of the results' parameters are removed but not the results themselves.
The problem is due to incorrect usage of radius in your Public Transit v8 API call. In your V8 query you have provided radius(r) as a separate parameter which is incorrect.
Please note the correct way to provide radius information in V8 is parameter in= {lat},{lng}[;r={radius}], where radius=500 meters by default.
You can also see the documentation in https://developer.here.com/documentation/public-transit/migration_guide/topics/stations-migration.html
Providing radius the right way(below query) fetches the required results.
https://transit.hereapi.com/v8/stations?in=50.7374,7.0982;r=90000&name=berlin&maxPlaces=25&apiKey={YOUR_API_KEY}