I had some problems grasping the… well, in the lack of a better description, core mechanics of the concept earlier, and this really didn't help me much. Probably has something to do with me getting your initial post completely wrong.
To clarify, upon writing something in the lines of…
-A Short Love Story-
Nathaniel: I love you.
Ivána: I love you too.
*leaning over towards Ivána* Nathaniel: Let's kiss.
*Ivána blushes* Ivána: Ok.
*Nathaniel and Ivána start kissing, and continue to do so untill Nathaniel's head explodes*
…the radio would turn after which you'd hear the characters voicing the… thing you just wrote. The characters would, however, be arbitrarily picked from the people you know, and would, in reality, be acting out the entire scene where ever they just so happen to be in the moment, despite them not necessarily being anywhere near each other. After the thing was over, the people involved would retain all memories of their behaviour. Well, the one playing Nathaniel wouldn't. Is that about right?
Apart from that, I have several logical issues abut the concept, the biggest being, why would a journal be floating around with a radio? I mean, if under no compulsion, why would multiple owners decide to keep both these objects?
The other issues revolve mostly revolve around the plausibility of several one owner/multile owners/unawareness of powers/awareness of powers/current state of objects/original state of objects/number of enteries/Foundation permutations which I'll refrain from writing down because it'd take too much space. Plus, first, these are mostly backstory elements that needn't be included in the actual SCP article, and second, while, for the life of me I can't see how the presented elements would fit into a story that wouldn't be stretching it, I'm guessing you had one in mind and I'd be an asshole to criticise something I haven't yet read.
Regardless of the backstory, however, I would suggest that you make only one of these an SCP, while making the other SCP-1. As in, making the radio affect any written material in it's presence, or making the journal affect the nearest radio, or somesuch.
May be make the the journal into a dream journal, that would make the reasoning as to why people ever wrote anything that can be played out in it a lot easier. And creepier IMHO.
But, in any case, write a log.