Took another look at the screenshot of your first post:
the palette on the left side says, that this step is of type NI_Python, which seems to be a Custom Step Type.
A short (search machine of your choice) query returns https://www.ni.com/de/support/downloads/software-products/download.python-step-types-for-teststand.h...
Without further investigations, I suspect this was the initial Python integration for TestStand which is kinda non-standard / out of date nowadays.
I see two options:
1.) re-install this package hoping for the localization to come back
2.) change your code to the current step types with the (as of now) full Python support
Note: Option 1.) might seem tmpting to do since it might work very quickly, on the other hand you are setting up a new system right now... why not doing things right instead of increasing technical debts?