SYMPTOM:
After importing French Translations in Strategy using the Repository Wizard, the blank English Translations are replaced with French Translations.

Translation before French Language Import.

Translation after French Language Import.
CAUSE:
This is a known issue in Strategy. Currently the repository translation wizard is not designed to handle null entries for languages included in it.
ACTION:
Currently this issue is being reviewed by Strategy for a potential code fix on an upcoming Strategy release.
WORKAROUND:
Place text placeholders in the English Translations column before importing the French Translations.