From the above, it follows that TE with all "checkboxes" unchecked is not SoD.]

Yes, that's correct; saying that TE with all options disabled is SoD is certainly wrong. Theoretically, there are very many differences that already exist, which were introduced so long ago that we (TE players) have already forgotten them.

And a player who hasn't played TE before the tournament is in clearly worse conditions, since they aren't used to, for example, slow being on the second level, and the Town Portal being in Fire Magic.

What is this about? Not entirely clear.

From a conversation with Horn, I understood that TE will never be the same as SoD

Yes, TP is in fire magic, slow on level 2, you can also rebuild the Mages' Guild, DD in water, and much more. And there is a logical explanation for all of this. Most importantly, no one is hiding it; there is a file where everything is described, all the differences :)
But the essence of the game itself hasn't changed at all; why does TP in fire scare you so much? If you don't know about it—yes, I agree. It's just that everyone who says they won't play TE is afraid that something was changed there, but not a single one tries to analyze why it was done :)
I'll ask another question of this kind—why do you play on SoD 3,2 and 4,0? Why not play "The Restoration of Erathia"?

Therefore, saying:

this means lying! :mad:

Yes, indeed, Gunnar is a vile liar, let's hang him :D He wants to deceive everyone and lure them into playing TE; the only question is why would Gunnar want that?