Google can be rather unpredictable in offering various versions of its webpages to various users, sometimes depending on the users' geographical location, at other times depending on the specific computer/device/browser they use, on the logged-in versus logged-out status, etc. There can also be different versions of the
logged-in status! (Say, a logged-in regular Google user compared to a "corporate" or academic logged-in Google
Apps user.)
I don't normally use Safari in iOS, but I have just checked it out on my iPhone and I
am signed in to Google there (regular Google, not Google Apps). I don't understand why you are seeing a completely different
mobile version of Google Translate on your iPhone, compared to my version of it.

In
my mobile version of Google Translate, there does not even appear to be a way to sign in/out of Google's site.
That we are getting to see such wildly different results while employing the same "trigger code" in Marvin, is mind-boggling.