Search NVARCHAR2 column not supported with full text search

As I understand, you need to use NVARCHAR2 column if you want to store data coming from different languages. You can use also VARCHAR2 column for this, but you will need somewhere to store code page for each row of data. And in the database you would have meaningless data that you could not search with simple sql query. Only using NVARCHAR2 column you would be able to see and query different language data at the database level. Using VARCHAR2 column you can achieve this only at the application level.

But then again, NVARCHAR2 column is not support using Oracle Text full text search.

So, what to do in my case when in my database I have NVARCHAR2 column, and know I want to create full text search index on it? Just do not tell me I need to convert it to VARCHAR2 column, because it is not simple in a real world scenario with already many existing clients and huge application code. Is there any other simpler way of doing this?