I need to do a lot of Google searches to find Persian synonym of English words, It's my job.

I use this customized google search, So that it only show the persian results:

https://www.google.com/?lr=lang_fa

But i have to search manually and it takes my time. If i could add this customized search to my Search Engines, I would do it by selecting the word, right-click and selecting "Search with" > "Google - Persian". But i couldn't do it.

Theres is a "Manage search engines" in the settings and you can add other search engines to Opera there. I tried to add the customized google search there, I did anything i could, But it just search like google does with the default settings!

Anybody can help me?

Thank you for your time.