Cheaper price doesn't always lead to as large increase in demand. There is only so much writing and translation that is needed. So lowering price does not mean that same amount or more money is spend.

On other hand companies getting these services cheaper can mean that they have less pressure to increase prices.

I think whole Jevon's paradox is misapplied. More efficient use of coal leads to more use cases as they become profitable. Which there was lot of. With many other things like writing or translation there might not be more use cases.