Welp with this one, i can't really help a lot in terms of "official" artwork, considering that older Monstercat songs usually relied on the Monstercat template (the older templates don't use artwork) rather than individual artwork. Though i do have a few songs i could comment on:
Bloodlip: http://djmatduke.com/track/bloodlip-ft-veela-hardcore-mix the original doesn't have an artwork, but the Hardcore Mix (non-Monstercat) that Matduke has on Bandcamp does have one. Sadly he doesn't have the original on Bandcamp (or in fact, any of his Monstercat releases, apart from Forgotten Kingdom, which he luckily made artwork for), so the closest to an official artwork for this would probably be a red tinted version of this artwork, without the "Hardcore Mix" text
Ampersand: both Stephen Walking and Soulero uploaded the song on their channels with a background instead of Monstercat-template artwork.https://www.youtube.com/watch?v=XgipcQ1xTug (Stephen Walking) https://www.youtube.com/watch?v=_bdlzFegkz0 (Soulero). I would honestly lean towards the artwork in Soulero's upload, because I do know that Soulero uses the official artwork for his songs in some of his backgrounds, where as Stephen Walking is less likely to do so in his older uploads (Shark City's official artwork, which was revealed by a cover animation, you know the ones Monstercat do to preview songs, isn't the same as the background Stephen Walking uses in his upload) and instead uses other backgrounds to add to his "random" factor.
Catalyst EP: wrong artwork. https://www.youtube.com/watch?v=qFZ9OQuL8bg this is the official one (this is Rogue's old YouTube channel btw
Waking Dreams: Waking Dreams is an EP including the original + remixes (this was when Monstercat never really uploaded EPs with just remixes of a song) so i'd say you should use the official artwork. https://soundcloud.com/lewismd/twothirds-waking-dreams-dnb-vip this is the artwork of the EP. If you want to do the original, keep this one for the original, and maybe you could make a night enviroment for the remixes.
Animal Instinct: https://www.youtube.com/watch?v=8CSkmOaWIcE despite what i said about Stephen Walking's backgrounds in Ampersand, i am not 100% sure if all of them would count as unofficial. This one has some text on it, so it is slightly more likely to count as official. Yours is good too though.
Ideekay: https://www.youtube.com/watch?v=uXi6mYLKndE just some text, with Ephixa chillin. pretty much Ideekay's artwork. Can you make a version like yours, but where the text says "ideekay" instead of "idk" and instead have the Ephixa logo on the right? Also have "ephixa" written below "ideekay". I do prefer to use official artworks, but your style has more flavor compared to the basic background Ephixa uses
Disconnected: https://soundcloud.com/pegboardnerds/pegboard-nerds-disconnected though i also found versions with a dark blue or red background, with a red or dark blue Pegboard Nerds logo, and "Disconnected" written below in PBN's logo font. Maybe have a dark blue background, with the PBN logo on top, and on the bottom having "DISCONNECTED" in PBN's logo font, with "DISCO" being rainbow-colored? Also with the PBN logo and the rest of the "DISCONNECTED" text being white or red?
I Remember: https://www.youtube.com/watch?v=GX90dr8ldSw Tristam's upload of the song. I did try making my own version of it though, here you go https://cdn.discordapp.com/attachments/162305205638004737/212638529241612298/Monstercat_Template.png (with updated artwork layout). Also, speaking of Tristam, here's an updated version of the Truth The Remixes artwork that i made https://cdn.discordapp.com/attachments/184405746308481024/234372851480788993/Truth_The_Remixes_update.png (although this has the new Tristam logo rather than the old one, just to let you know, maybe put it at Alternate Artworks?)
