Best tool. I am the guy who made the post on r/firefox Subreddit mentioning your add-on. It has over 350 upvotes now means people truly find your work amazing. However, a dude came in and posted that he reported your add-on for violating Firefox's policy. He wrote:
"It's good that you found another fugitive! I will immediately send a request to Mozilla to remove it for violating the policy: Add-ons must be self-contained and not load remote code for execution.
The fact is that Firefox prohibits any inline translator like Chrome. You can read about it here: https://www.jeremiahlee.com/posts/page-translator-is-dead/
And here: https://bugzilla.mozilla.org/show_bug.cgi?id=1589974"
This is his reddit profile: https://old.reddit.com/user/patrocl
From his comments so far, I guess he had made a similar add-on in the past which got removed from add-on store for supposedly violating some weird Firefox rule.. I think your add-on is in danger now. :(

It's not quite as ideal as the translate features in Chrome, but don't let that scare you off! It still works very well (probably 90% as well as Chrome's service). I left Chrome because, you know, Orwellian data collection... but I use a Russian site a lot, and I was afraid I would have to keep using Chrome for that; once installed and set to my preferences, this little gem saved the day. I HIGHLY recommend this translator extension. And with continued downloads and support, I imagine it will be indistinguishable from Chrome before too long. Thank you to the developer!

Great extension and translates in page! As good as chrome translation.

thank! Please add hotkeys to translate and display the original page! Since I use the browser exclusively from the keyboard (I use it "vimium" extension), it is inconvenient to grab the mouse every time to press the "translate" button.

do sada najbolji

Merci pour cette extension de traduction qui fonctionne comme sur "Chrome" (clic droit, traduction page dans le même onglet). Bravo. Je t'ai fait un petit don ....

Edit: le clic droit ne fonctionne plus depuis la dernière mise à jour ....

Gracias a esta extencion me quedo mas en firefox Gracias (Filipe Ps)

One of the best translation addons for Firefox.

It's very nice

Great work! It is even better than Google Chrome translator

Thats app is the best... good job

Bien, ça vaut la traduction de Chrome !!!