In a previous version of Ekos, I had been using the post-capture script with a command like the following: 120
to run a small python script that will trigger a camera shutter via a serial port RTS line toggle, with the passed parameter equal to the exposure time requested.

This worked great, but after updating to the latest Ekos I now see that the scripting functionality has been expanded to support Pre/Post job and Pre/Post capture scripts in its own "Scripts Manager" section under tools. I have not been able to get my previous approach to work under this, however - whenever I pass it a script with a parameter, the logs just give the following no file or directory error:
2021-05-16T01:33:43 Executing post capture script 120
2021-05-16T01:33:43 execvp: No such file or directory
2021-05-16T01:33:43 Post capture script finished with code -1.
(Order reversed from the presentation in Ekos for readability)

Removing the parameters lets Ekos find the script fine, so I worked around this last time I imaged by making a hardcoded version of the script with that night's exposure duration explicitly set in the script, requiring no parameters. This is, however, pretty inflexible as I'd need a pile of scripts with various potential exposure values to cover all possibilities.
Was the loss of the ability to pass parameters in these scripting fields an unintentional regression, a change in behaviour, am I missing some syntax or something else?
As an additional ask, do these fields have any support for passing "dynamic" variables obtained from the Ekos GUI such as the configured capture count, delay, gain, ISO, etc? I don't currently need this functionality, but I can envision future scenarios where such options would be quite helpful for further customizing external script behaviour.