The reds are mostly just learning that themselves.

They select lots and lots and lots of blue applicants for the study-abroad program. They send some to Mîr and some to Elendil and some to Federation planets and some to Cube's Earth along with some Elf program directors to give them Allspeak and assign them reading on local history and local governments and keep an eye on them.

The blues are pretty capable of being good cosmopolitan students of the multiverse!

Oh good.  Are they trying to explain the caste system to people or just embarrassedly not mentioning it.

They mention it when it comes up. They explain it as "religious reasons" if they have to justify something they won't touch.

Things take time. 

The wizardry corporations on the space stations start exporting boots and belts and gloves and jewelry of various enhancements. And crystal balls. These sell very well. 

They are great! People are delighted to have them.

Word eventually gets out about how five Amenta years ago the Elves had a war that ended with feeding a planet into a black hole.

Wow. That's pretty fucked up. Of course, the Federation students are writing home about how not even in a war a planet got sucked into a black hole and then Elendil put it back for the Federation with everybody on it. Maybe the multiverse just has a lot of fucked up stuff in it.

Cube had hella fucked up stuff and Vanda Nossëo aggressively fixed it. 

Yup. The blue exchange students in Cube are pretty weirded out by the slugs. They are pretty gross.

But now they're friendly! 

They don't find them threatening exactly just gross. There are no Amenta applicants to Amicus Terra.

Do they find morph too gross to participate in also?

Well, it's gross, but mostly in the sort of way that all biological things are secretly gross all the time, just more obviously. Some of them are too repulsed and others want to fly.

Eventually the study-abroad programs end and the Elves watch interestedly to see if there are any results when they all go home.

They have all kinds of foreign technology, both engineered and social, to share! They have made foreign friends who want to establish trade relations! They have picked up languages!

Well, it's something.

How is the persuading of other nations of reds to relocate going?

The canvassing helps a lot, especially since it can involve gossiping about the Prince in ways that are not easily traced by the clean castes. Lots of votes tip.

Oh good. Lots of reds are welcome.

The preexisting red residents are better at helping them integrate than the Elves are.

This is not surprising! Elves are happy to hand it over to them and to start recruiting them for emergency response teams.

Some of them are good at that too.

And the other ones seem likelier to call help if they're calling red help.

Only to a point, but yep.