BIP report use '_vl' view cannot switch language by user language preference

Use '_vl' view to extract data in BIP report, but it didn't display in correct language based on user's BIP preference session language. Given that, I selected

:xdo_user_report_oracle_lang and USERENV('LANG') which is language condition in '_vl' view, it turns out shows different result.

For example, user changed session to Chinese, the test result as below:

select USERENV('LANG') lang from dual -- US

select :xdo_user_report_oracle_lang from dual -- ZHS

I tried to add Before Data trigger with a sql as below, but still got the same test result.

Before Data trigger: