It’s only possible to proofread a string only in case it has a translation.
You may use next workflows:
Upload translation (the same file) with option “allow translation to match source stings”, as a result translations and sources would be the same
Copy source skeleton for each sting you have
Online Editor | Crowdin Documentation
Also, the possible way would be even not to proofread text, in case you need status only, upload translations as I said in 1 topic, build and download, open any tool like Notepad ++ and with bulk changer change all “translated” to “approved” statuses