It looks like Houdini 16.5.413 and later have support for Unreal 4.19. You can download a recent daily build at https://www.sidefx.com/download/daily-builds/ [www.sidefx.com] I think we didn't get Unreal 4.19 until everyone else did, so we couldn't add support in advance, (though I'm not directly involved in that area, so I don't know specifics). I'm not sure what's involved with updating the github, but I'm sure it'll be done eventually. I'll ask around.kimba23Welcome!
BTW first Post!
Grabbed the latest daily build but the windows installer only has an option for 4.18 so I tried manually installing it but it complains about incompatibility.