Oh right, this part. Took me a while but it is actually way simpler than it looks. You don't need to freeze the enemies, just kill the two of them, use the super jump to get on top of the inverted-T platform on the right, then use 2 fire dashes to get to the platform on the left, make your way to the highest point of it, and then again use 2 fire dashes to get to the platform where the fragment and the golden cube are.
I was just seeing if someone got it as their first ending but I also wanted a full save so thanks regardless
I had previously checked for a full save but the post is from 2024 so I don't think it's updated
Also, how to even get the "faux" endings?