Hi, brief summary of work done the last week.
I had installed the Multi Language Country Names (MLCN) module, and after studying it, decided to implement a similar extension for zone names. The zone names (and zone codes) mix with country names in some parts of the admin code - I haven't yet worked on the non-admin code, except to list which files dealt with or depended on zone information, and to note that there are potentially far more files to modify than for country names.
Since I worked from the MLCN module, I could create an installer, finding out just how fragile that method is also (if it breaks somewhere in the initial installer code), so having an SQL uninstaller ready is also important for redoing the configuration easily.
For the multi language zone names, I used a table zones_name that takes over the fields of the zones table, and adds language_id as does the MLCN module, and also zone_code_iso which is the international code for zones of countries (ISO 3166-2), similar to the 2-letter and 3-letter ISO codes for countries.
When editing zones one now sees the zones for all languages (I have not implemented a filter per language), but when editing a zone one has the ability to edit the zone name and zone code for each language, as well as input the ISO zone code. This code is now also displayed in the zones listing.
About the same amount of core files were changed for the admin side to implement this feature (countries.php was not required to be edited further).
When I have finished on the non-admin files later this week I hope I can put up my files for others to benefit from.