Discrete logarithm on Montgomery curve twist
So I guess I'll answer myself as I finally figured it out:


twist of a curve is a curve - all possible curves with same A are isomorphic to either $B=1$ (your base curve if you use usual curve) or $B=-1$ (your twist curve) curve, so just pick whichever and be consistent.
every Montgomery curve has Weierstrass curve. Your choice of B matters which one you get exactly, but end result will be same.
(not every Weierstrass curve has Montgomery curve, but you already have equivalent curve - your original twist curve)
so map points to Weierstrass form, get logarithms by baby step giant step (or other fast algorithm), map points back, for each prime on the twist you'll get two answers ($k$ and $-k$).
if there are z primes, then $2^z$ answers can be reduced to just $4$ in $O(z)$ steps with Chinese Reminder Theorem and filter.
that doesn't give you unique answer, but very small number ($4x4$ in my case), so you can just test them all.


I didn't completely follow the math for factors of $2$ and duplicate primes. Twist order has factor of $2^2$ and then only unique primes, that's presumably why it's been $4$ not $2$.

I'm sure there's some way to optimize higher powers of same prime, I just didn't need it.