Config::Simple is certainly a useful module in other contexts, and I'm generally all for using modules, if appropriate.  For the task at hand, however, it wouldn't really provide any benefits.

For one, it doesn't properly parse the config format in question (no .ini or similar, but some custom format for an ancient Fortran program), so using a regex substitution is much easier here.

Also, it wouldn't free me from checking for the existence of the respective option in all of the configs, and using a corresponding flag variable, etc.

Finally, it's not a core module, and installing it on every host the fixup script is supposed to run on would only create unnecessary administrative overhead...  But thanks for the response anyway.