Not exactly. Building a water profile and making final adjustments to mash pH are two different steps. First, you must have an accurate source water profile saved which includes pH. Next you need to create a recipe. After adding your hops and grains, hit the add water button and select your source water. Following that, you go to the water tab and apply the desired water profle, and finally, you adjust the pH as needed in the mash tab..
The ions in the water will influence the pH, as will the makeup of the grist. That's why you complete the recipe and apply the salt additions in the water profile before adjusting mash pH.
You can't get to where you want to go without knowing where you started and following the proper path.
The calculator is a tool to get you into the ball park. Without a quality pH meter that's the best you can expect. As with any calculator, the more accuraet the inputs are, the more accurate the outputs will be. One last thing, it's best to aim for the mid point for mash pH, or about 5.4. This will leave room for error in either direction.