Usually Nintex workflows are executed on the web servers which is why you should have all Services running there. There might be scenarios in which part of the execution is performed on the app servers but the services won't be needed there.
I see the relay service is disabled on web frontend 1. This service is only needed if you run anonymous public forms by using live forms to collect responses. So if you don't run these you should be fine. Otherwise consider enabling it.
Aditionally I recommend going through the installation best practices described here to ensure your farm is set up properly: