I can't do anything about a file being removed or deleted from your computer's filesystem. Save the file as opposed to opening it and it should stick around. It's a ts4script file so it doesn't need to be opened.
I haven't received any messages from modders who rely on it for their own mods so it's safe to assume that it still works for 1.77 and requires no update.
What sort of trouble are you having? If the file is being downloaded with a different extension you can simply change it back to what it should be. If that doesn't cut it you can join the r/thesims Discord server via Reddit. That's where I'm hanging out most of the time.