i have created a custom datalist. The datalist's Elements is associated to a custom type: CustomType. When i navigate to select the datalist's element to bind to CustomType, in my datalist there is a list of nodeId (i suppose) of the datalist's elements.
In datalist element, at the time of creation we not provide name, so alresco generates random name for it. That looks like nodeid, but that is not a node-id, if you want to change it, either show the name field in creation form or apply a rule to set some property of your datalist item as name, so you can the datalist item with some name rather than random id in selection picker.