score:2
Searching Timatic with your specific details I get this:
Transit - Namibia (NA)
Visa:
Visa required.
TWOV (Transit Without Visa):
Passengers with a confirmed onward ticket for a flight to a third country within 24 hours. They must stay in the international transit area of the airport and have documents required for the next destination.
Subject to these conditions, you don't need a visa to transit in Namibia.