I don't usually run into problems where "transfer data from X to Y" is it. Usually it's "there's data in CRM X and data in Event system Y, merge the two keeping X as the master source"
There's Mulesoft et al but they seem overkill for small deployments, as well as being stupidly expensive [1].
1. I'm sure they're good value if you're an enterprise company. But if you don't need the UI builder and only 2-3 sources kept in sync, they are expensive. And with my reading of the documentation, conflict resolution isn't great either.