I'm not quite sure what you need destination:ref:to for? If it should be the reference of the highway this (i.e. the first) highway is heading to, then you should be able to derive this information from the data already.
A short question regarding Mapillary: I tried it in Switzerland and more or less all signposts are pixelated like all license tags. License tags have to be pixelated, but why signposts? Or is it just a bug?