I'm not your target user, but I'm curious what happens to the pjm5bus_out.txt file that's generated. Can you somehow make that available to JS so it can be downloaded by the user?
I published this just to demonstrate that Time Domain Simulation was working to Hantao Cui, the author of Andes. Small Signal Stability Analysis will require SciPy and an ARPACK package. I would like to create a PWA that runs Andes in a web worker, like I did for MATPOWER:
https://matpower.app/