We won't find a cow in the pre-cambrian because we know they're not there, tends to be small lifeforms, note that pollen has been found in the pre-cambrian but evolutionists have labelled such evidence, "anomolous"
Actually, I would have lableled it 'spurious'. You refer to pollen grains in the Hakatai Shale, I believe. However, those grains were shown to be concentrated in cracks in the rock. They were also white in color, which is the nature of modern, not fossil pollen, and they are not flattened into the plane of the shale laminations as would be expected.
In fact they would actually just argue contamination, and I have read that they have done this before. They also cast doubt on potentially compelling evidence such as human footprints (Laetoli) or even the human and dino footprints found together. It is at least interesting evidence but in one book Dawkins just says it's fake even though they shown how it wasn't fake.
In the case of the Hakatai, the interpretation just happens to be correct according to all of the evidence. You can complain, but that will not change things.
Re: The modern coelacanth is an extreme deepwater marine fish
This article is about breccia that forms at continental margins. Perhaps you were referring to how slumping and gravity flows related to formation of Mlange would cover deep ocean sediments?
As the article says, there are multiple ways of creating a melange. In fact, if Faith wanted to make a case for some kind of 'under strata' deformation, some of these would be a possibility (although the rocks look entirely different since these are breccia and not layered sediments such as the GC Super Group ... it would be a huge stretch).
A discussion would be a bit off-topic, but suffice it to say that melanges tell us a lot about active continental margins (usually convergent boundaries - subduction zones, etc.) and the antiquity of the the planet. Look up the 'Franciscan Formation' in California for some interesting facts.