Fallback locale doesn't work

[KatieWoe]

Found during https://github.com/phetsims/phet-io-wrappers/issues/612.
The fallback locale only seems to work for one locale change at most.

1. Go to centerAndVariability.general.model.fallbackLocalesProperty in studio and set the fall back to "es"
2. Change to locale to most any other locale, and look at the Kick button (it isn't translated in many languages). It is still in English even though there is a Spanish translation.
3. If studio was in Spanish then one locale change will have the correct fallback, but the rest will be in English.

[KatieWoe]

This seems to be a more general issue as I found this in phetsims/qa#1034 as well.

[zepumph]

This effects all sims, moving to joist.