to build your own interpreter can get very complicated. Why not start with a simple state machine (search for this in the forum)? In the state machine you can create one state for each command. This way the user can create kind of batch files for test setups and your program will execute them...
Best regards, GerdW
using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
If you have a budget, and if it's for the long run, check out NI's TestStand. It is a system to execute VI's, dll's and exe's with a script. Not as much fun as making it yourself, but almost definitely cheaper in the long run.