Nope. Because they are not for sale in UK.Have you bought a Tributary yet?
I did buy a Cairn Brave back at Christmas with similar motor spec, battery size etc. Though the version I bought is flat bar - originally back in '21 when Cairn released the Brave they did a drop bar and flat bar version. The drop bar version was discontinued unfortunately, so I got the flat bar & have since put on some swept back bars which suit it & me. I might do a rider's report in a new thread if I get the time- it's great fun and I would have definitely have been interested in the Tributary if it was easily available. Especially as I already own a Vaya and that ladies and gentlemen is the bike I would grab from the garage to save first in the event of a fire, despite it being 15 years old and not worth as much as the Vado or Brave.
Also I don't think there are enough e gravel bikes out there to have a consensus (light or heavy) and anyway bikes like the Tributary or Brave as full fat big battery bikes are more about adventure & exploring with many purposes not just riding on gravel. They are at a gravel & mountain bike cross over/sweet spot. Salsa, who released the first gravel bike back when everyone else was on cyclocross bikes with the Warbird and were one of the first to commercialise fat bikes and also with the Fargo (steel) & later Cutthroat (Carbon) created a whole new type of drop bar MTB for adventure racing particularly the Tour Divide, seem to know a thing or two about riding bicycles off road and are not interested in just following the fashionable crowd. And that is a very good thing for choice.