Not sure about a declarative solution, but you can do this with javascript.

Johnny, yes, all of these can be translated using Translation Workbench. Skuid stores text such as “Check all”, “Uncheck all”, and “Enter keywords” in Salesforce’s “Custom Labels”. We provide Spanish translations for almost all runtime text out of the box, and provide translations in French and other languages for some of the more commonly used areas, but it appears that we do not have French translations for the Multi-select Picklist UI, unfortunately — BUT you can add translations yourself very easily if you’ve got Translation Workbench enabled!

1. Go to Setup > Custom Labels, and then search for the labels “Check all”, “Uncheck all”, “Enter keywords” that are in the skuid namespace.
2. Click on each of these labels, and then in the “Translations” related list, click “New”.
3. Enter a French translation, and click Save.
4. Refresh your Skuid Pages, and you should see the translations. If translations don’t show up the first time, try refreshing again.

Hi gents

This sounds promising.  I’ll give this a try, thanks.