Obligatory IANAL. Obligatory I am not staff, nor an agent representing Roblox. Obligatory these are all me speaking from my own person and of my own current standing knowledge and research.
Foreword: are you sure that channel is even representative of NCS? I’d encourage you to access NoCopyrightSounds directly rather than another channel that isn’t endorsed by them. The official NCS channel does not display that account as one of its other operated channels. You could be receiving secondhand or otherwise inaccurate information.
Right, so here’s the thing people often don’t catch with NCS: you actually aren’t free to use them in games. I guess the assumption comes from the channel name. If you refer to their Usage Policy, they have a specific header about the use of their releases in games. Games, regardless of their nature, are labelled as commercial use and require a license to be signed between you and NCS. Excerpt:
Can I use NCS music in my independent video game?
Regardless of whether your game is free to download, use of our releases in video games is considered to be a commercial use. A Commercial License Agreement will need to be signed between NCS and Game Developer / Publisher.
It’s important to assess the usage scenario of audio from a publishing label. If you aren’t able to find this information immediately, it’d be best to find a source of contact. I’ve made a more detailed post regarding NCS tracks in another thread regarding non-copyrighted tracks (not NCS), but due to a misunderstanding, I happened to cover NCS usage in games. Check that out here.
Here's a collection of all announcements regarding music copyright and DMCA action. These can serve as information resources if you need to understand the circumstances regarding punishment on copyright.
So yes. If you are uploading NCS tracks for use in games without that signed license and a copyright claim does get raised against your game, you will start accumulating strikes leading up to a termination. Copyright claims affect your ability to use the Developer Exchange program assuming use of unlicensed tracks falls under Section 3(F) of the DevEx Terms of Use:
Community member in good standing and at all times during your use of the Services strictly complied with the General Terms (including the Rules of Conduct and the Ongoing Service Requirements for Developers, set out in item 4 below). In our sole discretion, we may choose to waive any of your minor moderation infractions. But, by way of example, the following will make you ineligible for a Cash Out: scamming, phishing, false advertising, attempting to exchange Robux for real currency other than through DevEx, any illegal or unethical activities.
DevEx Terms of Use. Accessed 05 August 2020.
With the assumption that the information I’ve accessed remains accurate, you may email devrelations@roblox.com with the subject of “Licensed Music” and provide details about a track you’ve either created or signed a licensing deal with that was removed due to automatic flagging or other moderation actions. If you sign a license deal with NCS, upload the track and it gets flagged, then just send an email with the details to get the moderation countermanded. I am banking on two pieces of information remaining up-to-date as my sources.
If you have created or licensed music specifically for Roblox and you are concerned about it being removed as part of our automated process or it has been removed, then please email us at devrelations@roblox.com with the subject “Licensed Music” and provide as much detail as possible about the affected music.
Upcoming Music Changes and Copyright Related Action. Accessed 05 August 2020.
If you have personally obtained licenses for music in your game, please email devrelations@roblox.com with information about which songs were affected and the details of your license agreement.
Music Copyright Flagging is Live Today. Accessed 05 August 2020.
Regarding your secured permission with Unlike Pluto: you may want to also follow up with them regarding Roblox’s own rules about IP content. Roblox implicitly and automatically retains a license to use the content that you upload to the site (so like a sublicense to another entity by right of you uploading to Roblox). You may need to check with Unlike Pluto that they are alright with this. Refer to Roblox’s Terms of Service, Section 6B(3)b for further information. I’ll provide a relevant excerpt, but you may want to read the rest as well.
… in consideration of using the Service and the potential to earn Robux as discussed in the Robux section, you grant us a perpetual, irrevocable, worldwide, non-exclusive, royalty-free right and license (with the right to sublicense to any person or entity, whether a user of the Service or not) to host, store, transfer, publicly display, publicly perform (including by means of digital audio transmissions and on a through-to-the-audience basis), reproduce (including in timed synchronization to visual images), modify, create derivative works of, distribute, and use in any way the UGC that you Provide, in whole or in part, including modifications and derivative works, in any media or formats (tangible or intangible) and through any media, items or channels (online, offline, or others, now known or hereafter developed), including for publicity and marketing purposes (except that you are not granting us any license to make new or derivative video games using your UGC).
Roblox Terms of Use. Accessed 05 August 2020.
If you upload Unlike Pluto’s songs and they get claimed, refer to the above text regarding disputing the flag by emailing DevRelations with the details of the license/permission you hold for the action to be countermanded. Just be wary about the existence of this text in Roblox’s ToS.
Regarding remixes: I don’t know much about that. Remixes are a derivative transformation of the original work and I would assume that they also need to be in compliance with the license. I don’t know how things work when you want to use a derivative work of an original, so you may want to look up a bit on that or wait for an answer from someone more qualified to answer.
That’s all I know on the matter. Feel free to ask questions or correct what I’ve mentioned if it was wrong. I’m definitely not the best person to ask about copyright but I guess I do know a thing or two about how the whole spiel goes when it comes to Roblox.
PS: Do not go to Moderation Review Requests to dispute a deleted asset on the grounds of a copyright takedown strike, they don’t have the ability to handle it. You will be redirected to DevRelations to resolve the matter first and if follow up from them is required, they will act accordingly (in private).