AfD is (like BSW) extremely anti-Ukraine. Seriously, the party boss just called for recognizing Russia’s victory. That‘s the big divider, on immigration issues they could find common ground.
I'm not German, but it seems to me that CDU could capitulate on immigration in exchange for a change in AfD party policy on the Ukraine war. I doubt there are that many hardcore pro-Russian voters (although who knows with the East Germans).
So, merely noticing that Russia is winning and has been for a long time
No, it wasn't that. The AfD boss's remarks were not having a certain take as to which way the war is currently going. He was calling for German goverment to issue a diplomatic recognition of this "victory" - right now, before anything has actually been negotiated and settled.
The two positions may sound superficially similar -- but are in fact radically different. Apples and oranges, basically.
If this isn't immediately obvious to you, then I guess this is one of those situation where things that are obvious to others ... aren't obvious to you.
(which is ... acknowledged by Ukrainian-born pro-Ukrainian security expert Michael Kofman)
Except Kofman doesn't present the "Russia is winning" spin as you are implying. It might sound to your expectant ears like that's what he said. But it's not what he said.
He also isn't God, and other analysts have different takes.
There are plenty of reasons why Russia's incremental and very slow gains on the ground do not automatically translate to "Russia is winning", in view of other things that are happening in the conflict. Or why an assessment such as "Ukraine is unlikely to reverse Russia's gains"; or even a more blunt "Ukraine is losing" is not simply equivalent to "Russia is winning".