The language dropdown also gets updated with the updated column name, logically it is better when the alias is set that is the column name.
Since the view has multiple text joins with the column SPRAS. So HANA might rename each SPRAS column with a prefix to make it unique. This would have caused the problem with the language column you set as SPRAS.
The error could have been: ceInstantiateModel.cpp(XXXXX) : Failed to get filter attribute SPRAS
However, it is good that you did not get any error.
The answer to your another question to why we choose SPRAS as language column is that SPRAS is a standard field within SAP table that stores language key information, which is used with text joins, which is capable of changing the language of the generated data from the view user-created to the language selected by the user(you) i.e Chinese etc,
You can choose to select any type of join for the view but text join acts as an inner join so retrieves unique values.