Rahmi, it really depends on your recipe how much lye concentration will work best to keep your soap fluid enough to pour easily in a CP soap. Also your temperatures and how vigorously you mix will affect how quickly the soap comes to trace. If I remember correctly you don't have a SB, so at least that's in your favor if you want to avoid over-zealous mixing that can lead to 'soap on a stick'. I had it happen to me just yesterday, and boy it can happen fast! And that was with a 33% Lye concentration, which is equal to 2:1 water to lye ratio.
I have gone as high as 40% lye concentration, but only with high oleic recipe soaps, like 100% olive oil soap and hand stirring only. It did not cure any faster, in spite of being firmer and harder much earlier. Castile soap takes a long time to cure to the best it can be, and the amount of water makes no difference in my experience. But the good news is, the bars don't warp as much as they do at the (
lye calculator's) default amount of water, especially if cut too thin. I moved to chunkier sized soap to avoid the warp, but less water does that, better. AND you save of water if you use less water, so that's another plus.
But as recommended by dixiedragon, I agree that making sudden drastic changes to how you make a recipe isn't the best way to make changes. Perhaps you could use one recipe and do a test of 4 small batches within a couple of days of each other and try use different water amounts and no other changes. Then document your observations for each batch and over time. Make one a control, which would be your normal recipe with your normal amount of water.
Example:
Batch 1: Control (33.33% lye concentration 1:2 lye to water ratio)
Batch 2: 34.5% lye concentration (1:1.9)
Batch 3: 35.7% lye concentration (1:1.8)
Batch 4: 37% lye concentration (1:1.7)
I suggest small increments of change in water amounts for your testing because drastic changes are too different. It's better to see the subtle differences gradually to identify the one that works best for you in your recipe.