The audits will not go away. They are in place due several complains about reviewers not reviewing or misusing the review queues. Summary, reviewers bring this forth by themself. Now, if you seriously fails so many review audits in good faith, then go outside the queue and fix the issue you found!
Downvote, vote to close, edit, flag, etc. That's why there are many "ambiguous tests" due our inconsistency when evaluating the quality of a post. Things that should be closed are upvoted, things that should be upvoted are closed (this is just figurative, I haven't found a post in that state), spam is not getting flagged, etc. So, if you find that you failed an audit and don't agree with it, present an specific case so people can fix it.
Now, addressing your specific concerns:
Audits have become a large share of the review tasks, in my case about one third of the review tasks are tests.
Audits are totally random, is just bad luck that you get so many of them. I've had only ~20 out of all reviews I've done so far.
Many tests seem to be unclear or at least prone to ambiguous actions, creating a good deal of backlash.
I believe you should then dispute the review audits in the same fashion everyone else does. Post the specific audit you failed and why you disagree with it. Otherwise is just rambling.
A bug exists that allows users to identify tests - clicking on edit in a test brings up the message "This post is deleted [sic]". I am now able to avoid all audits using the edit button.
I'm sure that this is a known issue (can't find it in MSO), but most of deleted post are unsalvageable for anyone but OP so maybe you should instead cast flags over them.
Stack Exchange team is observing how audits behave (at least that's what they made us think) and will be able to fix any issue it's present. Again, if you feel that your action was correct due the state of the post, go and fix it, don't just continue without fixing the problem.
x2or similar test. Even if you get 10 audits in 10 reviews, you cannot conclude that they are not random.