SCP Foundation

Object Class: Keter

I would consider classifying this as safe. Once containment is established, all the Foundation needs to do is not test it and not let anyone access it. The information doesn't seem to have actual intention in terms of spreading, so establishing containment seems pretty plausible itself too (especially if it can take a form where it kills the infected instead of propagating.)

All instances of SCP-XXXX are to be stored in a 4m x 10m x 10m chamber at Site-92.

This is one of the concepts where exact containment chamber dimensions seem a bit silly. As long as it's sufficiently large to hold them all, it doesn't seem relevant how big it actually is. Not including unnecessary details in the containment procedures helps emphasize the specific details that are there, so I would recommend cutting the size requirement.

Any piece of writing partially or fully matching the description below must be reported to Containment immediately

I assume "Containment" here is referring to some containment authority, given the capitalization? If so, I would recommend using the full title of the department or person. Saying something related to containment should be reported to the relevant containment specialist or something of that nature feels a lot more credible as an in-universe instruction.

Electronic instances of SCP-XXXX are to be separated from surrounding circuitry before being put in containment.

I'm having difficulty envisioning how this would be accomplished. Do you mean the hard drive containing the file should be removed, or something else?

Persons affected by SCP-XXXX are to be terminated immediately, unless ordered otherwise by a member of the O5 Council.

This seems a little extreme, since there doesn't seem to be any reason for them to spread the information. It doesn't appear contagious between people beyond human decisions to communicate it.

SCP-XXXX is the text from a shopping list made by an unknown individual, most likely between 199█ and 2005. Although the list is written in ordinary ██ grade graphite, attempts to erase or add text have been unsuccessful.

I don't think the redaction here really makes sense in-universe. Redacting the final numeral of a year only creates a range of nine possibilities, and there can't be THAT many grades of graphite. I would just pick arbitrary values for each instead. Needless redaction really takes me out of a story.

Hopefully you'll remember it this time, ██████.

█████████ eggs

Similar point here, especially since the rest of the list is totally expunged. I think it's probably more reasonable, given the danger of the information, but the rest of the list was expunged anyway.

When the text above is fully written, typed out or otherwise stored, the recorded data will become "memorized", meaning the medium will become uneditable and immune to all damage.

Quoting specific words in this nature feels like a tonal break for me. You already explain what you mean by it, so there's no need to appropriate a word that means something narrower. That said, you may want to specify what you mean by uneditable, especially with physical mediums.

Addendum XXXX-A:

This is pretty typical in the "and then a bunch of people died" style of addendum. I would personally be more interested in seeing the effects of other portions of memory (or brain functions in general) stop working. How does the Foundation cope with that? You can keep the containment breach narrative, but explore a wider range of less immediately lethal effects. I personally think that would also be more interesting than the current list of experiments at the end.