The ribbon bar names are soft: i.e. you can edit them.
So a bit of Google-fu suggests: Right click the tab heading > Customize the ribbon > Click on the tab you want to rename. Either right click and select "Rename" or click the "Rename" button below. Then put a space before or after the tab title. The tab title will now appear in sentence case.
Or,
Fix the ribbon bar ALL CAPS casing on new microsoft applications automatically | Dream Walker
Usual disclaimers: not been there, not done that, stand back before pressing Enter, price of fish.