doesn't seem like that overrode the field as I expected. I see lots of examples in the repos of overriding a field at the top of the schema (not sure if that's the right word?) but none in a nested map - any pointers?

That looks like basically what I would expect - though I haven’t carefully compared with the underlying schema.. One example that is in a similar ballpark is: https://github.com/pulumi/pulumi-aws/blob/master/resources.go#L1829. Does that provide any useful pointers?

just figured this out

Resources: map[string]*tfbridge.ResourceInfo{
			"rke_cluster": {
				Tok: makeResource(mainMod, "RKECluster"),
				Fields: map[string]*tfbridge.SchemaInfo{
					"nodes": {
						Elem: &tfbridge.SchemaInfo{
							Fields: map[string]*tfbridge.SchemaInfo{
								"roles": {
									Name: "RoleList",
								},
							},
						},
					},
				},
			},
		},