Changing Language Key directly in lang_en.php file

I'm curious if modifying this file directly and re uploading will update the language key or do I need to do this thru the language settings on the backend of dolphin? Obviously it would be a world easier to simply scroll thru the lang.php file and change things all at once instead of searching and finding individual ones thru administration screen.

Please someone who knows the answer to this let me know before I attempt any changes. 

Thanks in advance.

To further elaborate on my proposed method. 

Step One: Export the language file via adminstration interface (as a backup)

Step Two: Recompile language file

Step Three: Export again. Edit directly, updating any and all key's desired in a much more easy and efficient manner.

Step Four: Save that file and then import it back, again thru the administration interface

In my logic this works wonderfully. But I read a post from several years ago where Deanos said editing the lang.php file directly was not correct. Please let me know if my method of doing this will update anything and everything as expected as an alternative to doing each key update via the search/modify on Language settings of administration backend.

Thanks.

Come on Dolphin Gurus... This should be a simple question to be answered by any number of veterans on this platform. Please let me know.

Direct editing of langs/lang-XX.php files isn't recommended since all changes will be reset upon lang file recompilation. 

Export/import is correct way for editing system language keys, but module's language files can be restored to the default values, so if you edit all language keys using this way - don't restore modules language files.

Modules language files can be restored via Admin Panel > Modules > Add & Manage > Recompile languages

@AlexT: Thanks so if I'm understanding correctly I can download the lang.php file. Make the changes and upload it and those will be seen where expected on the site. However if I ever restore the module language files they will all be lost... Is that correct?

Also, there is a recompile language option under the language settings

What role/impact does this have on any and all existing language files. Thanks for the input.

Yes, you are correct, expect this statement: "I can download the lang.php file", it meay be you mean export - then it's correct. 

"Recompile languages" will restore module language file, only module language keys are affected, other language keys stays intact.

"Compile" button in Languages Settings, just recreate 'langs/lang-XX.php" file, it doesn't change any language keys in the database.