Parallel transformer outputs
Saturation current is probably defined/measured with DC on the primary and they will be looking for a reduction in primary inductance as this dc current is increased. Note that they say "20% roll-off from initial" and this implies they simultaneously measure primary inductance whilst cranking up the dc current into the primary.

This means it has nothing to do with the output current capability when operating at high frequency AC.

I read the spec sheet as implying 36V AC@ 3A when all secondaries are in parallel.

If wired in series I would expect 3 times the voltage at 1 A.