Comment by diffeomorphism

For the translate part let me just point out the offensively bad translations that reddit (sites with an additional ?tl=foo) and YouTube automatic dubbing force upon users.

These are immediately, negatively obvious as AI content.

For the other questions the consensus of many publications/journals has been to treat grammar/spellcheck just like non-AI but require that other uses have to be declared. So for most of your questions the answer is a firm "yes".