I have not perused the code for mods to see if this is the actual cause, but testing so far appears to support this observation:

When transporting steam into a Turbine, most methods of piping steam in cap at 1000mB/tick rather than 2000mB/tick. This might be due to many mods calculating fluid transfer 10 times per second (every other tick) rather than 20 times per second.

Can you make a slight alteration of the code so that the steam flow rate adjusts how much steam can convert to water per tick, rather than how much steam can enter the turbine chamber per tick? This would allow the steam chamber to act as a buffer, accepting (for example) 4000mB of steam every other tick, but passing that steam to the blades at only 2000mB per tick.

Yes, that's a simple change. I'll think about doubling the size of the interior buffer as well.