Yes, NL becomes SR but usually they don't land on this lane because NL is very close to their docks so they like to use it for only departures. Even in high crosswind and tailwinds they prefer to take NL for departures....taxiing in water perhaps is not the easiest of things to do. It takes a lot of time for them to taxi to SL and SR is almost never used for departures because there is no taxi lane for SR and they have to backtrack on SR. And there is no point in taxiing to NR if wind favours a northbound departure. Thus NR is almost all the time used for landings and NL for departures. It's forbidden by procedure to use NL for landings because the final approach path runs over docked aircraft and terminal buildings of the seaplane operators.
And yeah, there is one more lane, West/Eastbound - a crossing lane. Depending on the wind these lanes are used for dep. and landings.
Our main RWY is 36/18 and almost through out the year we have a crosswind. No choice, it's on an island and that's how the island is.
I hope that gives a glimpse of our aerodrome.
Thanks.