Will electronic flash with correct filtration affect B/W film speed testing vs. using only natural sun light?

I found following (average values):

daylight around noon with clear sky and electronic flash have around 5,500 K

morning / afternoon sunlight ~ 4300K-4500K - flash with #3409 Roscosun 1/4 CTO (converts 5500K to 4500K) should be within that range

It looks like color temperatures should match pretty close. Are there other factors except just light color temperature which will make a difference?