"A new user? really?! Why would this help?" It's a good idea! In my experience, this often helps solve problems, and not only with scripts. It's easy to temporarily create a new account, try it, and if it doesn't help, remove it. If it works, it means something is wrong with the InDesign installation, prefs, etc. -- not the script. Also, you'll get a 'clean' InDesign version for a new user account: no need to reinstall it. Are these scripts in binary format? If not, you can install VSCode (Mac & Windows) or ESTK (only Windows), and try running the script line-by-line from there to pinpoint the place in the code where it hangs/crashes. Ideally, in such a situation, if the developer would debug scripts locally on your computer via TeamViewer. Also, can you try running it in the save version but on another computer? Did you try trashing prefs in InDesign?
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