Thank you for reporting this.
The reason is that we missed adding the new messages to the list after the column menu feature was added, we will update them as soon as possible.
These options are available for customization:
"filterClearButton": "Limpiar filtros",
"sortAscending": "Srden ascendente",
"sortDescending": "Orden descendiente"
This is an example with the column menu fully localized:
I have updated your Telerik points for bringing this to our attention.
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