While Google Translate's interference sucks, with current browser tools, I don't think they can really operate any other way.
This is mostly because of cases where they need to translate a sentence like "[Click here] for more information". When translating it to another language, they may have to move the link to the end e.g. "For more information, [click here]". The only way to achieve that is to shuffle DOM elements around, which can cause interference with interactive apps.
There's still a lot the Google Translate team can do to reduce the interference they cause, but I don't think they can fully eliminate it without some new browser APIs.