Let's talk about our Red Rush strategy...

Guys! The Red - rush in my understanding was something different from what I imagined it to be. I reread the rule and realized I checked the wrong box. I vote for points 2, 4, and 6.

I will take such errors into account, write about it in the thread.

Regarding possible influences on the outcome of a battle. Suppose Blue has a scout hero with non-zero magic and one snake, who has death wave dealing 50 damage in their arsenal. Red, unaware of this, attacks with growth. The first turn goes to Blue, they cast death wave, not all of Red’s units die. Red will then say they didn’t know about the death wave, but do I understand correctly that in this situation Blue will be awarded the victory? If I am that Blue, I will definitely demand that victory.
Suppose Red anticipated the speed and also brought a snake, but Blue accidentally forgot an artifact that gives +1 to speed on the scout, and the first turn still goes to Blue. Another tech loss? Is that how this will all work? It could be possible to deliberately set oneself up for a red rush with such cunning plans. Am I understanding everything correctly?

It’s good that you’ve not only "read" the rule but have also started thinking about its application. Keep in mind that you might be Red.
The clarification regarding Gates and Portal was precisely introduced because of one specialist in setups — hiding so as not to be seen and accidentally rushed.
In cases of insignificant Red Rush, players usually ignore it. If it’s really important for Blue, players often agree and replay the moment without the Red Rush. Judges are very rarely involved; the rule is detailed, understanding the situation is not difficult, and the player who committed the Red Rush usually acknowledges it themselves and writes down a loss.

Allow it everywhere, play a season, and draw conclusions.

There is no point in introducing it for just one season, look at the statistics of games on Diamond and Mini-Nostalgia for the spring season.
What conclusions can be drawn from 5–11 games over an entire season across the whole forum (about a hundred players are currently participating in the votes), especially considering that the possibility of a Red Rush occurs far from every game?
It’s more about the entire previous gaming experience and habits.

It would also be good to read Vic’s posts in this thread, after all, he is the author of many templates and wrote the theory quite clearly.