Hi!
Sorry I can't keep up with your writings as unfortunately I don't have enough time to check these. Yes, the pictures are very helpful. I compared your pictures ("ant" and last, I can not see clearly the middle mark) and yes I can see the some differences, I am not on a position to say what is a fake but as you both indicated that the "ant" like is a fake I am sure you are correct. I copied the mark on the spoons here just to compare and would say that it is somewhere between your pictures, maybe it has more similarities with your "ant" picture. The interesting thing is that the picture in Postnikova PL#2022 is also a little different from your marks in the pictures (especially the back part of the horse and rider).

I noticed that in your last picture it seems that the assayer mark seems to have been struck before the makers mark? Maybe it seems only like this in the picture but as you know it should be vice versa, I am not suggesting that it would be fake or something, it is just odd, maybe it is a human error.
What Lev Oleks did during the missing years, maybe he was on a sabbatical leave at the Black see taking sun. ;)
Of the oval mark that I have. It is struck on a sugar tong (inside) and the size is app. 4mm. Why an assayer would have several mark during one year, I believe the reason is that different marks where used for different objects, especially the size I guess mattered. I could not see that the trippel could have been struck on the sugar tongs as it might have broken it.
Regards,
Juke