A connection error usually means there is a server side error, can you check the logs/output.log when uploading an image in the composer.
Spelling error in Hebrew
When the system sends a new user invitation there is a spelling error, how can I change it?
The translations are at https://www.transifex.com/nodebb/nodebb/, you can fix the errors there.
But I did not find the option of editing strings to translate
You need to create an account and go to the correct language file.