Can repro. The translation from context menu seems to be broken in M61. 

Claudio, could you look into this please?

Translating using the context menu from a number of different languages (Japanese, German, Spanish, French) to English worked for me (61.0.3163.100)

I have also successfully translated a number of pages to Russian (but not using the context menu) using 61.0.3163.100.

The issue seems to be related to the specific pages in the bug. If I go to an arbitrary page and click "Translate to English" it works fine (even if it is in English). If I go to any of the specific pages, "Translate to English" hangs. I suspect there is an issue in the translate element causing this.

I confirm the issue encountered, e.g. on the website:

https://aviaforum.ru/forums/flight_safety/

Sometimes translation works, sometimes it doesn't, the failure is not predictable.

When it fails, it usually translates part of the page, then rolls back to the original Russian text and display "this page can not be translated".

I therefore suspect that some html tag/stuff in the lower sections of the page, perhaps in the bottom of the page, or scripts interfere causing the translation to abort and roll back.

It would be a lot better, if in this case the translation so far is kept and the disturbing element is just left out and translation continues after. Or if a script interferes the translation continues despite the interference.

The rollback (removing all translation and show the Russian original again) should not occur at all.

Okay, I think I just have found it.

I attach two screenshots, one the original which can not be translated and rolls back (russian_translation_original.jpg) and the modified one, which does translate (russian_translation_modified.jpg).

I found in the second list item the name of the last poster is "constructor" which apparently causes the roll back. When I modified all appearances of "constructor" in the two parts of the list item to "constuctor" the translation worked.

Deleted: russian_translate_error_original.jpg 292 KB

	russian_translate_error_original.jpg 292 KB View Download

Deleted: russian_translate_error_modified.jpg 280 KB

	russian_translate_error_modified.jpg 280 KB View Download

For easier reconstruction without depending on dynamic content on that page, here's the page sources saved out of my debugger. Again original version which doesn't translate (*original.html) and then the modified version which does translate (*modified.html), difference: two 'r' characters are missing in the name "constructor"/"constuctor"

I suppose the word construct or constructor causes the havoc possibly being a protected word.

Deleted: russian_translate_error_orginal.html 108 KB

russian_translate_error_orginal.html 108 KB View Download

Deleted: russian_translate_error_modified.html 108 KB

russian_translate_error_modified.html 108 KB View Download