Thank you for your question!
To my regret, there is no 'outdated' label for Storefront elements/ Store Components sections at the moment. But this feature was already added to our roadmap.
If the theme is being changed, we would recommend translating the Storefront elements section again as translations of each theme are unique, so that for the new theme new translations should be applied.
Please feel free to contact us firstname.lastname@example.org if any other clarifications are needed on this matter.