First things first: don't assume that the person you're having a discussion with "will be confidently wrong twice." That's not a discussion, that's an argument on the internet.

Now that that's out of the way:

Please cite primary sources. I will only pen my thoughts for one paper you linked that I read, since I suspect this is one more paper than you have read. I'd like to demonstrate how I approach a paper, even if I'm only scanning through it:

https://journals.plos.org/climate/article?id=10.1371%2Fjournal.pclm.0000010

It's important to actually read the papers to know how the research was conducted, and by whom. Case in point: the paper is written by the CEO of Impossible Foods. Could it possibly be biased at all, I wonder?

We assumed in all these hypothetical scenarios that non-agricultural emissions would remain constant;

I'm no expert, but that's not right at all. Just look at what datacentre buildouts are doing to emissions! This already invalidates their model, so now we are solidly in spherical cow territory. But let's keep going.

Our default model also assumes that biomass will recover linearly over 30 years, following [1], but there is considerable uncertainty in the literature

Assuming that land reverts completely to its native ecosystem without livestock is a daring assumption, considering grassland ecosystems co-evolved with grazing animals! No wonder there is "considerable uncertainty." The cows are getting more and more spherical.

we did not attempt to predict how global food production and consumption might change with growing populations, economic development, advances in agriculture, climate change and other socioeconomic factors. Nor do we tackle the social, economic, nutrition and agricultural challenges inherent to such a large change in global production.

Paragraph speaks for itself.

We calculated the combined impact of reduced emissions and biomass recovery

So this model only considers emissions and biomass (manure) recovery. What about, for example, soil health, water infiltration, nutrient cycling, or other factors that regenerative farming techniques try to optimize for? Or the old chestnut that animals can graze on non-arable land?

The cows are definitely very spherical now.

Existing crops could replace the calories, protein and fat from animals with a vastly reduced land, water, GHG and biodiversity impact, requiring only minor adjustments to optimize nutrition

Aha, there it is. The fundamental assumption that the entire paper is operating off of. This is unfortunately misinformation; plant nutrition is incapable of replacing animal nutrition, even if we only think of vitamin b12. But we also know about heme iron, the fat soluble vitamins ADEK, anti-nutrients, toxins, and so many other things. Read the community's posts to find out more :)

If you're curious, please start with "The Great Plant Based Con" by Jayne Buxton. Don't waste your time with these industry-funded papers.

p/s at least for this paper, tar wasn't wrong.