I'm the anon who was having problems with the Deleter paper.
So just for shit and giggles, I decided to buy the cheapest local brand of Indian ink I have available in my country. And to my surprise, it caused zero bleeding and zero feathering.
This thing was a fraction of the price I paid for the other inks, and it worked much, much better. It seems to actually be an acrylic paint sold as Indian ink. I have to clean my nibs more often, but as long as it works, I'm happy.