I'm looking at the https://arxiv.org/abs/1904.09193 paper (version 2, from 2021) and think it has a few errors. I think I found three small places where the paper needs to be corrected (in the sense that the corrected version is valid - none of the key conclusions are undermined by this).

On page 5 it says "Lemma 3.5. Let Q ∈ $2^{N_∞}$ be given. If Q(ω) = 1 and ∀n ∈ N. Q(n) = 1, then ∀p ∈ $2^{N_∞}$ . Q(p) = 1." I believe the second $2^{N_∞}$ should be $N_∞$ (because Q ∈ $2^{N_∞}$, you'd want to evaluate Q at an element of $N_∞$)

A few lines down is the statement "Theorem 3.6 ([Esc13, Theorem 3.15]). There is a function ε : $2^{N_∞}$ → $N_∞$ such that for every Q ∈ $2^{N_∞}$ , if Q(ε(Q)) = 1, then ∀p ∈ $2^{N_∞}$ . Q(p) = 1.". The last $2^{N_∞}$ should be $N_∞$ for the same reason.

At the end of the proof of that theorem, in "Hence Q(p) = 1 for every p ∈ $2^N$", $2^N$ should be $N_∞$ again for the same reason.

Perhaps this is a social question - how do I contact an author? - but I also wanted to post here to see whether what I am proposing is right and in case other people are hitting this when trying to read this paper.

P.S. I formalized these proofs at https://us.metamath.org/ileuni/nninfall.html and https://us.metamath.org/ileuni/nninfsel.html in case that helps.