As far as testing the RNG. As per OP and…The recent development, which has been fixed! Thanks @Petri!
I’ve dabbled with this a bit:
I basically modeled my research after Garanwyn’s:
Only where he tracked 3-2, I tracked mono.
Unfortunately… I no longer have access to it, as all of my work is now locked up in a phone I can no longer access…
So… where he found 0 starting boards without tiles. I found 9. Collected the screenshots and continued my compilation.
Until… I got really bored of playing mono…
But the outcome after about 400 samples on my end was a graph that looked ALMOST like Garanwyn’s
Except my graph was shifted to the left (I did have 9 at 0, not all were mine, I had help)
and had a slightly steeper ascent. Which I believe was settling had I continued to add samples.
Anyway, analyzing data can get tricky… some people are very clever at twisting information to fit their narrative… I’m one of those people… but I try not to be.
For now my take is simply, the more you stack the greater risk you take for Random (or seeded whatever 
) boards.
But honestly I feel the research is incomplete…
We got that “middle road” data at 3-2
And I lost the right curb mono data… But it tracked as expected…
Now I want the left curb, bad boards for Rainbow Teams!
Which in my opinion will be the most telling and damning information about a biased RNG!
Bad boards for rainbow do exist! This happens when you suffer 4 rounds of only one 3-connect option. And usually experience the board reshuffling! Which is probably, what really needs to be counted…
When I was baby match player, I played rainbow. And I remember the board reshuffling. Then I grew a little, as did my bench… and started toying with mono, 4-1, 3-2… and did the board shuffling subside? I really can’t be certain… I haven’t been counting.
I’d have to start over with my tracking…
And I’m overwhelming exhausted at the thought of that. Can you imagine fielding 1,000 rainbow teams in this current raid environment?!
Anyway… I could care less if the 20 pages of code have some hidden disclaimer somewhere. The game remains fun for me regardless. Especially with 2-2-1. I’ve been loving on that for months now!
And if it’s the same code that everyone else deals with? phew…
Then who cares. Stop taking mono and you won’t notice the 0 boards so much. I promise!