I recently made the comment that “it isn’t as if the Sartarites get up to Glamour very often” – but let’s not forget, it is only about 700 km from Glamour to Furthest. It takes about a week and a half or so to get from Boldhome to Furthest. From Furthest, one could take a boat to Raibanth, so let’s assume that goes 50 km per day, which gets you to Raibanth in two weeks or so. Another day or two to get to Glamour.
That suggests we could probably do the trip in four weeks if we pushed it, probably a season is more realistic (stops for food, trade, looking around, getting permission, getting in trouble, etc.). That is still quite doable. So expect there are Sartarites who have been to Glamour. Maybe even more than a few.But I doubt they get invitations into the Inner City or get to go to the Imperial Palace or Moonson’s parties. Whew!
As we know, in the Fifth, Sixth, and Seventh Wanes, the Lunar Empire often sent treaty wives to various barbarian kings. I suspect there were emissaries sent to negotiate this marriages, so presumably there is an emissary tradition. If the Lunars do it, so do others I suspect.In fact, we know that there is a tradition of Emissaries in Dragon Pass. So presumably Tarkalor and Terasarin may have even sent the occasional emissary to Glamour (to talk about stuff like caravans and so on). And maybe after 1629 we see that again? Who wants to be Argrath’s emissary to Glamour during the Civil Wars! 
This is why I think it is far more realistic to assume a trip from Boldhome to Glamour would take a season or more.Not just that walking eight hours a day, day after day, is tiring. But things need to be arranged, gods and spirits placated, people seen, important people need to be gifted or bribed, bandits avoided, etc.
As an aside, this is part of why Sartar’s roads are so amazing. Paved, with regular caravanserai, shrines, rest stops, AND protection? Wow!
Going from Boldhome to Furthest is probably pretty easy (at least to Slavewall). I imagine the King of Tarsh personally gets too much money from the Furthest terminus of the Dragon Pass Road to do more than tax it. But from Furthest downriver? Everyone wants a piece of that action, and the Red Emperor probably takes a cut every time.
I wouldn’t say most Gloranthans “never travel at all”. For example, most Sartarites travel to their local city several times a year, and many to Boldhome at least once a year.