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.

@patmat when i click that italian link it gets changed to uk
but i notice the site has a selector at bottom of page try that maybe

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