For spell check or the user interface? Is there something wrong with adding Hebrew in Opera's settings? Goto the URL opera://settings/languages and click on "Add languages". Hebrew is in there and available for spellcheck after you add the Hebrew language.
I do not use ubuntu or gnome (or unity, if the screenshot is from 16.04 or older).
All the opera's .desktop file mentions is 2 entries that are only available under unity: one for launching it as usual and one for launching it in private mode, so I assume the other 5 come from gnome or from some gnome extension.
However, since opera is closed source, there is no ppa for it, you won't find anything to translate it yourself.