“They already acknowledge at the sixth seal that the wrath has come.”
Not quite. They say “the great day of his wrath is come”. Firstly, the great day of wrath is a singular event, prophesied of in many places in the Bible, so we have no excuse to mistake it for some long, drawn out, years-long event. Secondly, “is come” doesn’t mean the same thing as “has come”. “Is come” can mean the same as “is upon us”, or “is imminent”, referring to a future event that must take place shortly. The future tense of this phrase is confirmed by the next phrase, also in the future tense: “who shall be able to stand?”
No it's a period of time.
Matthew 24:29 And immediately after the tribulation of those days, the sun shall be darkened, and the moon shall not give her light, and the stars shall fall from the heaven, and the powers of the heavens shall be shaken;
That's multiple days. In Daniel's prophecy we see that the time left of the 490 years is seven years (one week of years). All of the events of Revelation occur during that seven year period.
>>Secondly, “is come” doesn’t mean the same thing as “has come”.<<
The Greek has past or present tense "has come". It is not a future anticipated event.
>>The future tense of this phrase is confirmed by the next phrase, also in the future tense: “who shall be able to stand?”<
That statement doesn't stand the scrutiny of the rest of scripture. Here is the literal word for word from the Greek:
"because come did the great day of His anger, and who is able to stand?
It says " come did" and "is able". Not will come or will be able.