Localization: One table or multiple tables? (MySQL)
This is clear example of Many-to-Many relation (M:N).
Many messages can have (be translated into) many languages.

Date structure for that has three tables:

create table Message (
  ID int primary key, 
  message text
);

create table Language (
  ID int primary key,
  language varchar(50)
);

create table Message_Language (
  message_id int, 
  language_id int,
  contraint Message_Language_Message_fk foreign key(message_id) references Message(id),
  contraint Message_Language_Language_fk foreign key(language_id) references Language(id),
  constraint Message_Language_PK (message_id, language_id)
);


It's more modular and you can add more languages easily.

What kind of queries are you performing on the tables.
Provide more info about complete data structure (and other tables).

Are you aware of data normalization in RDBMS?