Hello,
I've deployed quite a few Node.js and ExpressJS apps on Heroku. I'm familiar with Heroku Add-ons, custom domain setup, dyno customization and few other settings which may or may not be needed depending on your project.
I read the docs at KeystoneJS and it should be compatible with Heroku.
Please share your application files so I can take a closer look.
I'd be happy to answer any questions over chat.
Do contact me whenever you are available.
Mateen