You can use a tool like JOSNViewer to format the JSON.
Also make sure your files are properly UTF-8 encoded.
And check the line endings whether UNIX style or Windows style (CR+LF).
Sadly I have to inform that I went ahead with my conclusions…
all 3 files were encoded in ANSI (acording to my notepad) and Thats why they worked WELL - on my PC. Error doesn’t come from extra spaces and linebreaks but from resaving in UTF-8. If I open en-us.lang (any of *.lang) in my Windows notepad and simply resave in UTF-8 without any other editing I got a ParseError from Json… (mine korean version of Win7… maybe makes mess??)
I tried editing with Komodo Edit and there are no problems… Sorry…
I would not recommend Window Notepad for coding.
Use Notepad++ instead:
… or Microsoft Visual Studio Code: