Well, a week is not a lot of time to debug possible breakage of multiple scripts over hundreds of installed modules. I hope you have a good test suite :)

CPAN does store old versions of modules (many, not all) so if you have a record of versions, you may be able to recover the original software. Also, packages are stored in the authors directory of the cpan working directory -- if you do not clean that out often, then you may find copies there.

Probably the easiest approach is to hand build on one machine, checking for errors (you need to do this, because while the modules are unchamged, the compiler, glibc, etc. may be) and then rsync to the other machines.

Note that many of the modules you find may already be installed as part of the core libraries of perl. It would be easier if you surveyed the scripts to see exactly which modules are use'd or require'd. It may be fewer than you think.