Hi Eduardo,
UG: https://blazor.syncfusion.com/documentation/common/localization
We suspect that you might have overlooked the necessary
locale for today's text in the localization file. Please check your
localization file to ensure that the locale text for the Today button is
present, as shown below. If our assumption is correct, include it to resolve
your issue. We have prepared a Blazor Schedule sample with the 'pt' locale.
Give the shared sample a try. Refer to the shared UG for more details.

For customizing the date range header, as you mentioned, you
can utilize the Schedule’s DateRangeTemplate,
as demonstrated in the code snippet below.
[Index.razor]
|
<SfSchedule TValue="AppointmentData" Height="650px" @bind-SelectedDate="@CurrentDate">
<ScheduleTemplates>
<DateRangeTemplate>
@((context as DateRangeTemplateContext).StartDate.ToString("ddd, MMMM dd, yyyy"))
</DateRangeTemplate>
</ScheduleTemplates>
</SfSchedule>
|

Regards,
Venkatesh
Attachment:
BlazorDateRangeLocalization_ef7b8553.zip