I feel the simulation for Benthic Bracers misses someone things out, yes Benthic Bracers maybe better than 455 mythic braces but you do not account for mythic bracers with a socket or in the simulation use the Bis bracers. Changing to BiS (from the article) and added a socket I get.Benthic Wrists (Frost Damage) @ 425 with Gem 47,372 10.1% +4254Benthic Wrists (Pufferfish) @ 425 with Gem 47,278 9.9% +4270Raid Wrists Bis @ 455 with gem 47,140 9.6% +4132Raid Wrists @ 455 with gem 47,084 9.5% +4076Yes the Benthic Wrists (Frost Damage) @ 425 with Gem are still best but not by so much and the stamina you lose over the raid drop is going to be significant.
Easy way to farm Perla de maná prismática would be the chests you open in Nazjatar. Pop the Piedra de visión and go crazy in Kal'Methir or any area with ruins of a village. Vaina de coralhondo will make it easier for people who don't have flying mounts that allow them to loot whilst flying until you get buffed from opening a few chests with Vista Arcana and Vientos deslumbrantes. I am not quite certain, but there also seems to be an invisibility buff if you open a few chests promptly one after the other (couldn't find the spell though).