Uff.. I am not an expert on these type of tags, but how I understood this old proposal (https://wiki.openstreetmap.org/wiki/Proposed_features/Destination_details#destination:ref:to) it should be destination:ref=CT 159. The destination:ref:to tag seems to be used for roads that are up ahead, not those that the exit directly leads to.

Feel free to join osmus.slack.com and post a question there. There are more people that understand this better than me.