Niara is claiming an internal pattern within the data, that somehow each number rolled is dependent on the rolls before it.
It would require many more data points to demonstrate that claim as you are trying to attach significance on mini-runs within the larger sample of data.
Using representative sample size as you are referring to is only meaningful when examining the full data such as with the average of the data points.
According to Niara's own spreadsheet BG3's dice rolling demonstrates the same randomness as the other games as the averages on the spreadsheet shows.(with 85% confidence.)
To demonstrate that BG3 sequence has unique internal patterns the person making the claim would need to do a large number, say 10,000 rolls for each game and then show that the patterns that show up in BG3 data don't show up in any other data.
Alternatively they could just make up conspiracy theories based on insufficient data and imagined patterns.
Provide some evidence that 10,000 rolls as opposed to a few hundred would be necessary to identify such a pattern. Either find multiple sources that support your claim or fit the data given by Niara and show that a horizontal line (pure random) is equally a good a fit as a sine wave. ~500 rolls is enough to statistically determine that a d20 rng is producing non-uniform results (it can detect even a single number appearing too frequently or not enough), so it should also be good enough to detect a pattern in the rolls. In fact, you should need less data points to detect a pattern because you're adding extra information: the order of rolls.
Otherwise, I'm going to accept all the sources I've found that claim that a few hundred rolls is sufficient for a good sample size. The clear pattern in Niara's data, combined with my analysis of 508 unweighted rolls and 750 weighted rolls, show that Larian's unweighted rng is not
uniform and produces an overabundance of '17's and underabundances of '1's and '6's.