I’m not sure this should be a person, more of a relationship, much like DevOps how works. DevOps is a set of ethics/guidelines/rules/* rather than a person or a role. I feel like this should be the same thing.
Instead of hiring or making people the bridge, existing roles need to be updated and people need to be more attuned to how the other side works. Engineering needs to be aware of the technicallities of design & UX, but it also goes the other way; designers need to be aware that implementing the design might not be simple.
I think mostly this comes down to working together. Bringing the two disciplines closer together and working in co-operative way.