We do have case feet replacement on the website - but I'm not seeing specifics for the 200R unless they are the same style for 230T.
Take a look here: https://www.corsair.com/us/en/Categories/Products/Accessories-%7C-Parts/c/Cor_Products_Accessories_Parts?q=%3Afeatured%3AproductCategories%3ACor_Products_Accessories_Parts_PCComponents_Cases%3AaccessoryType%3ACase%2Bfeet&text=&pageSize=12#rotatingText
If that doesn't help, before you go super gluing anything, you could ask Tech Support for their recommendation: support.corsair.com
For the 270R, you can add fans up top as they would help the heat curve (see picture) and expel more of the hot air inside of the case.
Although I have seen cases that have a cover on the top to create more of a "tunnel" to direct hot air out of one single rear fan. I've seen more of that setup with air coolers as their directing airflow right to the rear exhaust fan anyway.
Hope this helps!
If you have the time, try plugging the fans in sequential order in the controller of how you'd like them to appear / show up for lighting (slot 1, 2, 3, 4, etc.). Don't 'skip' a slot.
If that doesn't work, I'd recommend reaching out to Tech Support.
I would reach out to Tech Support as they might be able to better assist you once they get some info from you about Motherboard, Bios version, etc.
https://www.corsair.com/support
Is it just not as 'thick' as a normal hard drive? I've had that issue before where I just had hold an HDD up with one hand and toss a screw in to hold it a bit higher before I was able to screw in the others.
Saw this image online and just wanted to ask you if this are thicker than your HDD?
We do sell a replacement IO - but it's the entire unit itself: https://www.corsair.com/us/en/Categories/Products/Accessories-%7C-Parts/PC-Components/Cases/Carbide-Air-540-Front-I-O-Panel/p/CC-8930155
If your button fell off, you might be able to unmount your current IO, and put the button back in it's place and re-mount.