Hmm… so you know, generally the shotgun approach doesn't work that well, since most ideas require some detailed thought put into them to be viable. Three out of your four ideas are inherently "thing that does a thing"—there's no backstory, no storyline, no bigger-picture narrative for your reader to be interested in. While as a straight concept "thing that does a thing" is alright, keep in mind that we've got hundreds of those things on the site already, so your object will need to have some sort of unique aspect that will interest a reader.
- How would the memories be "slowly replaced"? How would anyone know that the memories are being outright replaced, and the person isn't hallucinating? How would anyone be able to pin down the effect to the bed itself? Also, wouldn't it be some sort of bunk bed? Furthermore, if you're going to introduce a topic like the Holocaust, you'll need to be careful with handling the concept tastefully.
- How would anyone discover that the janitor's cupboard is anomalous? If it's empty and it looks like a regular cupboard, why would anyone notice? At this point the idea seems to be more of an anomalous object than an SCP that would merit specific Foundation containment.
- The joke is cute, but it'd only make sense to people who know and understand the "lost their marbles" idiom. You can try writing it up and seeing how many people catch the reference.
- Most things that alter time can be tricky to write up believably. For this case, if it "permanently increases the speed at which you experience time", how would that even work? Successive speeds based on how long you look at the thing? How would anyone measure that? How would anyone even tell that something is happening if they don't look at the clock for that long?
Keep in mind that as the author, you know the entire story, but the Foundation needs to have discovered what it knows about the SCP through observation and experimentation. As you write, you need to make sure that it makes sense for someone with no prior knowledge whatsoever of the object, using only experimentation and observation, to come to all the conclusions you plan to state in the article.