For me, the point at which Perl makes more sense is if your script requires more internal logic than it does depends on spawning other programs.
For example, if I'm writing a routine to auto snapshot ZFS / Btrfs volumes and delete any over a certain age, the script would be dependant on your file system CLI tools. So it makes more sense to have an 80+ line shell script than it does to write that in Perl / Python.
However if I was writing a routine which requires users inputting details, where those details need to be sanity checked and then stored some where (such as a database), then the core logic of that program resides within your script (where you'd have to read inputs, do your sanity checks and then write to the database). So a Perl or Python script makes more sense.
Obviously you can do either of those examples in each of those languages (crudely speaking as I know shell scripts aren't technically a programming language); but that's just a basic example of where I personally draw the line.
I also think this is one of those occasions where it doesn't massively matter which approach you take just so long as the code works and is maintainable (though I draw the line at one maintenance script I saw last year. It was a Python script where every other line was os.system. It just struck me as rather pointless starting a Python interpreter if you're just going to use it like a shell script - you might as well do the whole lot in the shell to begin with).