In general, yes, through several intermediate steps; he's never met Nayoki, but Leareth was in communication with his people before being captured, and sent a diplomatic party to inform King Randale of why he had, well, sort of half kidnapped Vanyel. (The agent who found him did ask him first, just, he had about five seconds to think.)

No one in the other Velgarth knows about Bella's existence, though, since it hasn't ended up being relevant to any requests for aid, yet, and they're pretty sure this isn't a trick by Melkor at this point but aren't totally sure Bella and the others are operating in good faith here, and are being paranoid. 

I want to get the Nayokis in touch but if yours can't be led to expect me I'll want to start by addressing someone it's slightly less risky to startle by being in telepathic range of.

:Right, 'Mindhealer' and 'works for Leareth' would seem like a bad person to startle. Er, if it's a specific Mindhealing thing you need, I'll probably know off the top of my head if Melody could do it. And I'm confident she wouldn't hurt you even if she were surprised: 

The idea is to catch this one up on reasearch projects.

:Oh, fair enough. Melody couldn't help with that: 

Melody is great but yeah. Is it possible to tell her about me or should I bug somebody on my list first instead to warn her?

:Nayoki? I could pass a message for her but it’d have to go through several layers of people so I don’t know how long it’d take to reach her:

Okay, thanks anyway. Uh, your local alt has agreed to chat with your Leareth; do you want to talk to him about what your relationship with him wound up being like?

:...Wow. Me at eighteen... Sure, could do that:

So she goes and finds her Vanyel to lend him the earcuff for this purpose.

Then they'll spend the next candlemark talking, unless Bella asks for the earcuff back first. There's a lot of catching up to do; this conversation is even weirder than the last.

Afterward, though, local Vanyel tells Bella that he feels somewhat more confident he'll be able to hold a reasonable conversation with  traumatized Leareth, at least on his end. He wants to know if there are topics he should avoid because they'll upset Leareth a lot, though, having a lot of firsthand experience with that. 

"It's hard to predict exactly. I think going slowly in general and trying to be unflappable is more important than topic management? I doubt you're going to start talking about torturing him for no reason and if he has other triggers I don't know them yet."

"...Um, right." Vanyel shivers. Being as unflappable as possible is kind of his default way of interacting with Leareth, so that should be manageable. 

"It might be a while before he wants to see you, and it might be he can only tolerate it for a few minutes," she says.

"Mmm. Well, you can tell me, and I think Savil will cover for me on short notice if I say I have important reasons even if I don't say what - er, I haven't actually explained it to her because I wasn't sure if it was private and I think she's still pretty wary about Leareth in general." 

"Yeah, that makes sense."

Vanyel doesn't think he has other questions right now. 

Then she will start trying Nayoki's teammates.

Number one on the list is reachable but not in Mindspeech range of Nayoki, due to switching facilities. (They are also SO CONFUSED.) 

Person number two is just as baffled and suspicious and unsure what to think, but admits to working with Nayoki. 

Yeah, it's confusing, I acknowledge that. Can you be a relay for me - I'd like to listen through your ears and tell you things you can tell her, I can do that without picking up anything else I shouldn't - till it would be a good idea for me to talk to her directly?

Sure, that's still a strange request but she can do it. (She's less weirded out than she might otherwise be, due to knowing about one other world already, a copy of their world is weirder but honestly not by that much.) 

She goes and finds Nayoki and explains a bit. 

"...All right, what do you have to say?" 

Your alternate self would like to catch up on your research projects. We're in contact with your world's Vanyel and some of the Quendi he's with already but apparently communications between you and they aren't good enough that they could warn you, so I did this instead. I didn't want to contact you directly because the artifact I'm using closes distance for mental communication and mind-altering Gifts in both directions and startling you could have been a bad idea for that reason but I'm happy to switch any time if you promise not to try to melt my brain; I've never actually tested my shields against Mindhealing and don't really want to.

"What year did you say it was, in your Velgarth?" 

792, autumn.