easy and effective alternative:

1. Go to the URL opera://flags/#sidebar-site-panel
2. Enable the highlighted flag
3. Restart Opera
4. Click the 3 dots at the bottom of the sidebar (the sidebar options menu)
5. Scroll down to Custom Site Panels
6. Click add new panel
7. Past google trnaslate URL
8. Here we go

@brownnote: I was thinking exactly the same thing. this bothered me a lot