So it does seem to be just a theory, BUT...

[Blackjack Gabbiani]

So remember how I kept asking about the Rotom thing and are we SURE the diary belonged to Charon like the notebook did?

Well, I asked a Japanese fan about it and she basically admitted that it's a matter of preference, but she had this to say in a later conversation after I showed her Bulbapedia (we're talking about aspects of fandom):

By the way, Bulbapedia taught you was seen. It is very interesting to see Bulbapedia. Information has been very long and plenitude. What I had not known was able to be read too.

However... the page of Charon is not good. That page has put out an informal conclusion to the problem that has not been decided yet. English fan would rather write, "He has the possibility who is the author of the diary" there than write, "He is an author of the diary". The reliability of the entire Bulbapedia is sure to go up, too, if it does so. The information site is absolutely careful. A positive proof and an untrustworthy information site are bad. Even true information becomes unbelievable due to a part of the mistake.

But Bulbapedia is interesting and fun. It is true.

and also this, regarding the notebook itself (the one signed by Charon):

1.When this is written, Pluto doesn't know Rotom still well. He got to know Rotom, and wrote this at once. Certainly.
2.This notebook is the one obviously written by the adult. It is clear from this expression.
3.Pluto is writing, "I obtained <information> about the Pokemon Rotom." If he was a diary child, it does not write like this notebook.

At least, the Japanese fan can consent by this notebook. But... surely, they read in Japanese. It might be a Japanese locution and be a nuance. If it is so, I do not have a possible clarification any longer.
I wish that Ms.Amber and the English fan agree.

So while it seems to be a matter of fancy to put the diary with Cyrus, she's adamant that it's not clear who the writer was.

And I brought up the matter of the card game and she said that it's not really taken as canon.

 

[Umeko]

Any chance I could see the Japanese text from the game?

EDIT: Got the text of the notebook, and there does seem to have been something lost in translation, in terms of nuances and such.

 

[Blackjack Gabbiani]

Oh? Like what?

 

[Blackjack Gabbiani]

Not to double post, but I'd ended the last part in a question and...yeah.

Anyway, was anything decided about this? Since I know it wasn't just a matter of translation, as people were reporting it as they played the Japanese version. Perception maybe?

(although I still don't think it was possible for it to have been Cyrus, even if it turned out not to be Charon. Just an unknown third person).