The customer had installed the French - Canada language plugin.
After the installation had complete, he noticed that the sys_choice records for the Incident.subcategory filed which were installed by the French - Canada language plugin are completely different than the ones he has in the English language.
I was looking at the sys_choice records in your instance:
Comparing them with the OOB records on my instance brought me to the following conclusion:
The choices you have for the French language are all those with values that exist in our OOB data. Their labels / depended fields values are also the same as the OOB data, which is why it is different than what you have in your English choices.
When you install a language plugin, it does not install translations for your customized records, since it does not know how to translate them. The plugin will just install OOB translation records.
If you deleted some OOB choices, the plugin will not install their translations, however, if you modified a sys_choice, the plugin will still find it according to the value of it, and will install the OOB translation for this choice.
Next step for you will be to update the translations for the French language. You will have to do it for every sys_choice record which is not OOB. Either new ones, or ones which were modified.