I'm pretty sure the desire to question Tylee comes from the fact that she would have been living with CV and LVD when CD paid his visit.
Talk about the wolf in sheep's clothing... poor CV confided in exactly the wrong person when he went to AC.
As to the Tylee question above, I'm guessing this adds a lot more to LE's need to talk with her, because it also opens up the fact that CV and AC clearly had, according to CV, a good relationship prior to Alex randomly up and killing Charles. They probably want Tylee, at minimum, to say what she thinks or knows about when the relationship changed; and why this didn't come up in part of her witness statement to the Chandler police.
Maybe this will open some doors in CR's mind about some of his texts and chats with Tylee, retroactively.