Charles,
I wonder if other ways would be more appropriate for your situation:
1. Does the string that needs to be localized really change that often that it needs to be configured separately from an app release? If not, using standard localization features of Android would be much simpler.
2. If this is not possible, you could load all localized strings at once (either via Remote Config, or other Firebase products like Realtime Database, or any other way for that matter) and then select the correct one based on the device locale's getLanguage().
3. Last but not least, having a good enough fallback value for those cases where Remote Config cannot be updated (not just because of throttling, but simply because of offline devices, areas without wifi and/or cell coverage, ...) seems to be a necessity, anyway.