Lost camera on a tokaido main line?

Hello, I was on a tokaido main line going from Kyoto to Osaka. I didn't hear my friend say this was our stop and rushed off but as a result I forgot my camera on the window of the seat I was on. I called immediately after and filed my camera into their system. I was told they would call my airbnb host if the camera was recovered but it's been a few days since then. I'm actually leaving Japan soon and was wondering if there's anything I could do to actually help find my camera assuming someone turned it in?

I assume you called JR. Call again, and ask for all possibilities about how and where you camera may show up. Here is a list of JR offices where they have English speakers.
https://www.westjr.co.jp/global/en/support/

If you're already away from Kyoto/Osaka area and find it difficult to contact English speaking JR staff, just contact a major JR station near you.

Basically, whatever is found in JR premises are to be kept within the company for a week before it reaches the police.

I did call and they said they would contact me if something pops up. So I'm not really sure if I should call anyways or wait...but I'll try calling. I'm leaving for tokyo in several hours.

It's normal to call again. I do it all the time, and sometimes things come out and sometimes they don't. They won't be bothered by it. On the contrary, it would be a good reminder especially because items often turn out a few days after it is lost. It's no use calling many times a day, but calling back once in a few days won't hurt anyone. Good luck. And again, be sure to ask all your options!