Can I use Calculator Row parameters in a calculation in the Applies To column of a price calculator price engine?

Yes, but it does depend on how the calculator row parameters are named in your price calculator price engine. Names that are a single word will work, but names that contain spaces, or potentially other reserved characters, will not work. For example, in this example price calculator price engine, the calculation in E25 reads the value input as the Sides parameter in the calculator rows of A22 and A23.
The calculation references the Sides parameter in the calculation. If Sides equals 1, then the calculation returns 2, and multiplies the Unit Price to get a flat $12 fee added. If Sides equals 2, then the calculation returns 1, so a flat rate of $6 is applied based on the unit price, which then gets marked up to $12 by the 100% markup that is applied when Sides equals 2.
This works because the name of the calculator row parameters is a single value with no spaces in it. If there are spaces in the calculator row parameter name, then the calculation will fail, but it will not be obvious why it failed. So for this example, the calculation ifn(Sides="2",1,2) will work, because the parameter is named Sides.
Trying to name the calculator row parameter Number of Sides would not work, these formats would fail, and the calculation would not get the result expected:
ifn(Number of Sides="2",1,2)
 ifn("Number of Sides"="2",1,2)
The example price calculator pricing engine worksheet used here can be downloaded and used as you like. For more information on Price Calculator Price Engines see the article Ch. 013. Creating a Pricing Calculator Pricing Engine