As for the bigger picture of how does this effect the election and Trump's MAGA agenda? Simple, it doesn't. Manafort's conviction is meaningless for that no matter how much the media tries to spin it. If they keep spinning it they will just lose more of their tiny remaining credibility. So they'll basically drop it.
Just Google Manafort 300 years & you will see all the news outlets reporting 300 years for the 18 counts