How to know the right charge temp?

First time I start to learn how to roast green beans is what the cutting-edge software called? They are doing the logging on the laptop while roasting a coffee. Are these things really needed, only for coffee? First time I see people using the roast logging is in Coffee Bluer in Bekasi

And start from that, there are so many things can impact our coffee, and the one came from how they are doing when they roast the coffee, which approach they use to decide their goals.

And finally, we find something from the very first time until now, we still not getting the answer. The question is "How to know the right charge temp?".

After some research we already get some article that explain those, the first one came from Hartanzah and the second one is from Indonesia Specialty Coffee. From Hartanzah, they already put some calculator to decide the charge temperature, but not really specific about the other things (like duration and drop temperature). While Indonesia Specialty Coffee is more interesting, they already put all the others variable should be focus on. We think we need to do a comparation for that, but they only using the ordinal, not a nominal, that makes some situation maybe can vary.

And finally, we start to collect some roast data, for getting the linear model for deciding the charge temp when the others variable already known. By using 4 variables (Drop Temp, Duration, Density, and Yield) we can estimate the suit charge temp for that profile. The calculator just simple as below:

Based on this, we start to compare the actual and the predicted:

As we can see, the difference is not that much, and we need some adjustment from this model to get more precise charge temp while the other variables in known already.