'Every time a tenant takes possession' can certainly comply with a reasonable person's interpretation of "regularly".
If you take it out of context, sure, but ideally we wouldn't do that.
Investigators with every cause to be concerned about the whereabouts of knives could easily ask for such an inventory as part of an investigation into what should be there.
This is getting increasingly silly, irrelevant and detached from reality. I think if you want us to come to agree with you that AK and RS did it you two should be focusing your efforts on more important matters like the phone records, the state of Meredith's stomach contents, the clasp and knife DNA and so on.
The existence of a kitchen knife in RS's house wasn't a secret as far as I'm aware. Any number of people besides the landlord could presumably have been questioned about whether RS's house had a kitchen knife, and confirmed that such a thing existed at point or another. There's no way any remotely sane person would think that they could cover up the fact that RS's house at one time had a kitchen knife.
However this would have been absolutely no impediment to them saying, if they are indeed the criminal genius/idiots you want them to be, that they broke the knife a week before the murder trying to cut a frozen roast or something and chucked it out. Reasonable doubt, boom, done. Even if they didn't bother to replace the knife, which was apparently a perfectly common model, they're still safe.
(Well, safe unless their hypothetical blood-spattered clothes and the supposed two murder weapons are found, which if they were guilty they would have to be worried about that point. Unlike Rudy they don't have a nice big stretch of time in which to dispose of such evidence safely, so I guess they just got really lucky, right?).
So the argument "they had to take the knife home and clean it, or else they would be totally busted when the landlord inventoried the cutlery drawer!" is silly on multiple levels. The landlord wouldn't have done that, but there are plenty of other ways it could have been established that RS owned a kitchen knife. So it's silly on that level, but it's even sillier than that because they could easily have replaced the knife anyway (because the landlord's inventory almost certainly did not include any details about the knife), and even if someone did do an inventory before they could replace it absence of a kitchen knife would not be proof of anything. From every angle they would have been much safer putting the kitchen knife with their bloody clothes and the other murder weapon to vanish forever without a trace.
However does this make any difference to the argument as a whole? If it does I don't see it. If a given chunk of the guilter story makes no sense if AK and RS are smart, that's no problem, you just assume they were idiots for that part of the story, and they disposed of all the other evidence but took home the kitchen knife. Everything's consistent with guilt if you squint hard enough.
Whereas from the perspective of the defence story, there's simply nothing to explain. So either way, no difference.
That's why I think this subtopic is getting increasingly silly. It looks to me like you've stopped trying to make a coherent story and you're just hunting for nits to pick whether or not they are relevant. The same comment applies to your argument about the door furniture: It's been shown that the actual door almost certainly couldn't be opened from the outside if both locking mechanisms were enabled, because the relevant manufacturer produces no such device, but you're picking a fight over whether such mechanisms exist at all in the universe. Who cares? I suggest you focus on aspects of the story that are
actually relevant to whether AK and RS did it.