Hi JAAS,
I'm sorry for my late response. I understand your concerns regarding changing the ref tag. Most NIC-nn and NN-nnn road tags were originally added between 2012-2015 by myself under my main OSM username "miluethi". I thought like you that name and ref tag for a highway should be identical. But this is not true. The "ref" tag stands for numbers or codes according to OSM wiki. This tag is used for the highway "shield", which should be as short as possible, I would say 3-4 letters max. Full MTI names can be long, like "NIC-20B1" and the shield often doesn't show on a map because they are too long.
I was looking how OSM communities in Latin America use the ref-tag for highways. There is no clear standard, but Costa Rica, Panama, Columbia and others normally use only numbers in the ref-tag.
I also understand that not everyone might agree using such short ref-tags in Nicaragua and the OSM community might want to reverse this ref-tags. This can be done relatively easy. I generally created route-relations at the same time as changing the ref tags, so the ref tags can be selected and changed very easily.
Let me know what you think. Contact me through my main OSM user account miluethi, you should receive as quicker response.
