Hello,
First, directly answering to your question, if you want to have diffrent nominal value for same measurment parameter, Gael is right: you need to do a virtual probe copy of Kh but this is not feasible as of now.
Now, ased on my experience,even if you had the virtual probe of kH possibility, there is a lot of chance what you want to do will not be efficient:
I'm missing some inputs on your case so my answer can be not adapted to your case.
So first, my questions:
- What is your daily kh consumption? Means, if you do not add any kh (cut Klkwasser reactor and Calcium reactor), what is the daily decrease of kh of your tank?
- What is your kalkwasser reactor and how do you using it: standard way means :
Are you using limewater (translucent part is injected in aquiarium)?
Or are you using the milky part(whitewash)?

- what is the natural pH of the bac: max and min ? when you do not add anything to the tank?
- how often you measure the kh of your aquarium daily?
Depending on your answers:
Kh Consumption: if your daily kh Consumption is low (less than 1° kh per day), you don't have so much "kh credit" to use to influence the pH.
pH: need to know how much your pH need to be boosted or not. Naturally good condition istank where ph is at lowest, at least at 8.
If you are using the standard way (limewatter) as Calcium hydroxide is not very soluble in RO water, so you will not be able to bring a lot of Kh and you will not also have a remarkable effect on the pH.

If I were you, I would (i suppose you are using limewater):
1- started by putting off the calcium reactor,
2- measure Kh of the aquarium.
3- Put in place all osmolation going thru kalwasser reactor.
4- register pH and Kh evolution.

If Kh is stable after two days, it means that compensating 100% of your evaporation with limewater, is equal to your kh consumption.
If Kh had decreased, it means that kalkwasser reactor used this way can not recover your kh need.
If Kh had increased, it means that you can not do 100% evaporation compensation thru Kalkwasser reactor.

Then you have also to observe your ph during these days. To see if pH goes two high, was ok? or remains too low?

Please answer my questions and I'll try to guide you as much as I can.
Regards