Sure, though the first Friedmann equation, or any other equation, where terms are balanced, e.g. a + b = 0, doesn't tell you anything about causality, though re

Sure, though the first Friedmann equation, or any other equation, where terms are balanced, e.g. a + b = 0, doesn't tell you anything about causality, though redshifting of light is exactly caused by expansion, so it is not strange that both are "balanced".