Ask HN: Variable Cost Calculation for Quotations

I hope you can help me on this one, since I was unable to find anything relatable on HN or elsewhere:

I am currently building a variable cost calculation function for cost quotations. Craftsman and Installer should be able to create a variable cost quotation for their service which works for different sizes of buildings. Such as the installation of a heat pump or air conditioning.

The calculation should look like this:

(variables are given by the system)

cost block A: variable_1 x 100

cost block B: if variable_2 = true +200

(add all to get the sum)

The current setup works as follows:

1. Create calculation in Form (DnD)

2. Convert to json-logic `https://github.com/jwadhams/json-logic-js`

3. Save to Database in json field

-- Display Product or Service --

4. Get json-logic from DB and apply for each cost block with variables

5. Return in API

6. Display for Customer in Front End

Am I missing something, is there a better way?