There's also a design consideration. It is changing the capitalisation style to "Sentence case" to match the new design.

But this issue shows that we can't enforce that with style rules. We have to let the translations choose capitalisation style instead.

There's a question about what happens if the translation is missing for the tab name. There's currently some special handling of that case. But a missing translation should be considered an exception, we don't need special handling to format it, we just need to add a translation (in the style chosen for that translation).

So I suggest we remove that special handling.

(For reference, for a missing translation the default Rails behaviour would convert order_cycles to "Order Cycles". Our code would convert it to "Order cycles" to meet the desired capitalisation style. However, we don't need that special handling because we should add the translation instead.)