Sweet list,
I personally would cut most of the non-evasive pirates (unless they have a high impact), as they do not reliably trigger your commanders.
From what I understand you anyway plan to combo and have a high power deck (B4), so there is no need for lord effects.
You could swap them out for some more 1-2 cmc evasive pirates and add 2-3 more effects like Coastal Piracy, to draw through your deck more quickly for tutors / combo pieces.
As you are running Glint-Horn Buccaneer as a 1 card combo with Malcolm, I'm also not sure if it is worth to invest so many card slots in your other combos (Reckless Fireweaver/Ingenious Artillerist + Maskwood Nexus/Runed Stalactide/Arcane Adaptation), as you are just sandbagging if you don't just tutor for Glint-Horn IMO.
In the end it is personal preference, but I would either cut Glint-Horn or probably cut 2 of the creature type modifying cards to make room for something else. Also Niv-Mizzet Visionary feels like a win-more card here, as you only run 3 burn cards (excluding Glint-Horn here, as he already wins with Malcolm alone). Niv-Mizzet, Parun or ... Firemind at least can serve as another backup combo with curiosity/ophidian eye.
I would cut:
Captain Lannery Storm
Captain Storm, Cosmium Raider
Captain Vargus Wrath
Coastline Marauders
Departed Deckhand
Niv-Mizzet Visionary
Xorn
Maskwood Nexus
Arcane Adaptation
Unstoppable plan
-More Tutors (relatively cheap):
Pyre of Heroes
Long Term Plans
Drift of Phantasms
Dizzy Spell
Other possible inclusions:
Tandem Lookout
Cloud Pirates
Talas Scout
Talas Explorer
Scrounging Skyray
Stormfleet Aerialist
Kitesail Corsair
Coastal piracy
Bident of Thassa
Reconnaissance Mission
Enduring Curiosity
Kediss, Emberclaw Familiar
Professional Facebreaker
Windfall
Frantic Search
Underworld Breach
Some MDFCs for basics, if you don't want to get flooded with all your card-draw:
Valakut Awakening
Sea Gate Restoration
Pinnacle Monk
Sundering Eruption
Sink into Stupor
Hydroelectric Specimen