I wanted to merge two localization files generated by 7 Days to Dialog, but they contained the same static keys that would conflict with each other and they also contained some auto generated keys that would conflict with each other. The chance my be low, but as long as there is 0.0000000000000000001% chance, it is risky to merge two localizations without first checking each line inside the first localization.txt for possible conflicts with all the lines in the other localization.txt you want to merge the first one with.
As for cvars in 7 Days to Dialog, they are pretty straightforward. What I had trouble with is crafting and passing my own cvars in xml. I hope someone could teach me how to do that, because that would be just awesome and allow me to set more values more dynamically. For example, I wanted to let the NPCs set their own random hire cost. Didn't work, no matter what I tried, it always showed an error in the console telling me that the value was not in the correct format. Just an example of what I was hoping to be able to do with cvars, but kept failing to make it work...
Also, I've noticed that in your Samara quest, you have two dialogs.xml. Dialogs.xml and dialogs2.xml. Is it actually possible to use both at once? I thought that custom xml names would be ignored by game? Well, at least that was the information I got
here.