Hello
The best way to translate our plugin is to contribute to the plugin.
Of course, you can translate the plugin with locotranslate, but those translation are only stored on your local environment. I can’t tell you for sure if those changes will be overwritten when you update our plugin, but I think that’s quite unlikely.

The pro version of Admin Columns contains also the free version, so our plugin also consist of two translation files.

– Translation file for Free version managed on GlotPress (French translation)
We will include the translation files when we build a new version. Or you could download the file and put ‘codepress-admin-columns.mo’ file in /wp-content/languages/plugins/

– Pro translation file managed on Transifex
You can create a free account there so I can add you to the French team and start translating. All translation will also be included when we build the next release.