DE will ban me if i do some change with localization file ? i mean modify language file....

Quote

You agree not to do any of the following with respect to the Services, as determined by us, as applicable:

• attempt to reverse engineer (except as otherwise permitted by applicable local law), derive source code from, modify, adapt, translate, datamine, decompile, or disassemble or make derivative works based upon the Services or any Content;
• remove, disable, circumvent, or modify any technological measure we implement to protect them or any of their associated intellectual property;

https://www.warframe.com/eula-us

If you have suggestions for how we can improve the game's localization, please contact Support to do this in a way that doesn't risk your account.