It seems to me that I’m translating you using complicated ways 
1. why do you need to upload a file? it is easier to immerse the full list of text in a hidden text box. another language in another hidden text box, etc. 2. you can ignore the json markup altogether. the sequence of lines separated by a sign (a group of characters or special characters) is easier to overtake into an array and work with it using the same algorithm.
Your method is 1. slow. 2. A lot of blocks 3. inconvenient when editing…
it’s easier this way:
textbox1 - full text in En
texbox2.- full text in Es
these are instead of files.