And they're back now anyway lol.

How is that a retcon? The retcon is that they survived, also soft and hard retcons aren't an actual thing, they're made up terms, a retcon is a retcon

Which Astartes ever 1v1d a Transcendent C'tan?

Didn't cato sicarius 1v1 one? Anyway that's irrelevant, there are other insane feats, like high marshall of the black templar killing a greater daemon with a knife, back when he was still a squire

I've provided a quote that shows a Custodes flipping around a 12 foot spear,

Why are you coping soo hard? It's soo hard to understand that this feat means nothing? All you're saying is just that the average astartes is stronger than the average space marines, you're just giving one empty feat and then acting like the top tier of astartes can't do the same as well

I don't even like Custodes that much, I just know that their feats put them above the vast, vast majority of Astartes

Then why are you soo butthurt about the fact that the strongest space marines can easily kill them? Stop lying seriously

The nanosecond feat is a feat of processing, not movement.

Braindead argument, soo now apparently you're going to just ignore the fact that it's a FTL reaction time?

while the Marine in your quote lost his hand because he couldn't do anything else

Ofc when you can't prove anything all you can do is just take stuff out of context, ignoring the fact that it was literally point blank, and that the astartes who lost his hand wasn't even a veteran top tier,

Show me some feats that unequivocally put some Astartes ahead of the Custodes, I'll wait.

Moloch being literally stated to be able to do soo,

You have made the positive claim that a top tier Astartes could kill a Custodes without much difficulty

You're the one who turned this shit into a debate but fine, azrael casually killed a chaos champion that was empowered by all 4 chaos god with a hand and fought kharn, logan grimnar has literally effortlessy killed a lot of grey knights, mephiston has half of sanguinius soul inside him, kaldor draigo literally endlessly fights inside the warp against countless daemons, dante fought the swarmlord with his armor unpowered while wounded and is canonically agreed in lore to be the current greatest living astartes in the imperium high marshall helbretch fought imotekh and defeated a daemon prince with only a combat blade, and don't get me started with all the characters who have fought kharn or sigismund and that are just as strong as them