curaga, I created a patch for the getlocale.sh script (part of getlocale.tcz). I hope it's helpful.
The purpose is to give the user a red-letter warning in situations where the script is unlikely to work as intended:
1. if the script is running while a prior mylocale.tcz is loaded
2. if the localedef step fails
3. if the generated mylocale.tcz has a nonsensical size
Any of the above warnings would have prevented me from chasing my tail when using getlocale.tcz in the recent past.