Is this normal? Any of the Japanese Worlds installers I find on this site just don't seem to work. They'll open, and then they'll close after a second of what looks like loading. I just want to get the MIDIs out of my favorite clients (music wise), being Cha Cha Ra, Boo Boo Chat, and Eco Chat...

I imagine it's compatibility issues, but they should all run as they have been tested.
If you just want soundtracks, all the MIDIs are available here: https://files.worlio.com/files/WorldsChatJapan/media/soundtrack/

Oh shit, thank you so much for uploading them! Last time I checked, there were only 4 folders, so I wanted to install the rest of them to get the soundtracks out of them. Thank you so much!!
Do you also happen to have any images from Cha Cha Ra? I'm mainly looking for things like the thumbnails used for the YouTube uploads of the music, or any other general screenshots.

Yeah, I had them all already ready to go and just hadn't uploaded them yet.
I know they work on Windows XP (32-bit), so you can try them in an XP VM. The assets are in the CMP format, so you'll need CMPview to grab them.
Don't know of many screenshots.