Gave this a quick look, comments made as I read. I won't comment too much on wording, since as you mentioned, English isn't your first language.
- The formatting is way off. Take a look at the How to Write an SCP Guide, "templates" tab. There's some basic article coding there, please use that. Your headers are too large, improperly bolded, and the text of the containment and description need to follow immediately after the headers, not on the line below.
- "unlit ten (10) by ten (10) by ten (10) meter cube" —> Generally, the number (#) numeration is used for extreme precision measurements that can be fatal if misinterpreted, like drug prescriptions. You don't need to do that here, and especially not with easy-to-measure numbers that don't even have a decimal point.
- The use of "primary containment"/1CS is a little confusing. Why not just break up the paragraphs into similarly-related information and just note "inner containment" and "outer containment" or the like?
- The beginning of the description ("SCP-XXXX has been secured in █████████, Himalayan Mountains.") belongs in the containment procedures. Try to start off by telling the reader what the SCP object actually is and does before you give details on location.
- I don't buy the "computer animation" note. It just looks like a flat black circle. If you really want to use that caption, you'll need a more believable image.
- Try to avoid using words in "scare quotes". In-universe, the person writing the document is a professional, who knows the correct terminology to use.
- "SCP-XXXX continuously creates an absolute zero - exact zero degrees of Kelvin (0° K) – in its directly surrounding area, as measurements constrain" —> I'm not entirely sure if this even makes sense. Wouldn't it wreck the physics of the surrounding environment?
I had to stop reading before the addendum because I really didn't have any clue what was going on. It's a dark ball thing that eats energy? Maybe someone better-versed in physics would understand this, but I was just having trouble figuring out what this thing actually did, and why it was Keter. Why does this thing exist? Was it meant to accomplish something, or does it have a goal of some sort? What's the bigger story here?
At this point, I recommend getting the basic idea cleaned up in the Ideas and Brainstorming forum before you try fixing the draft. Right now, the concept just doesn't seem interesting enough to me, partially because I don't really understand it, and partially because the small bit I do understand I feel like I've already seen before in tons of sci-fi and fantasy works.