I wouldn’t run multiple servers.
I’d run one server with multple routes instead.
or use the user/broadcaster ID included in the POST payload to determine where to send store data.
So I’d have one server with one route and process/relay data based on the contents of the message
And yeah I’d use nginx to SSL terminate and proxy pass to my node service(s)
Course, for this I don’t use a library anyway (just express for inbound HTTP and all my eventsub logic is custom based on https://github.com/BarryCarlyon/twitch_misc/tree/main/eventsub/handlers/nodejs )