The pair originate in the 2001 Tag & Bink Are Dead comics which are, technically, part of Legends. (Though even there the comics were considered “Infinities,” which today makes them doubly non-canon.) How much makes it to screen (and canon..?) Well, probably not much. But that’s fitting.
Technicalities aside, the original Tag and Bink comics (by Star Wars Tales MVP Kevin Rubio) are among the highlights of Dark Horse’s run with the license. They’re totally worth a read, require nothing at all in knowledge of the vast Expanded Universe, and are really, really funny. I don’t think there’s been any physical reprints since the comics license changeover to Marvel, but the collection is available on Comixology.
Honestly, this is exactly the kind of EU appearance I expect in this film: Brief and irreverent.
There’s also a new Trailer Council podcast, featuring Amanda Ward (Making Star Wars, Rebel Grrrl,) Chris Taylor (Mashable, How Star Wars Conquered the Universe,) Shana O’Neil (SYFY Fangrrls,) Kyle Newman (Fanboys,) Steele Saunders (Steele Wars,) Anthony Breznican (Entertainment Weekly,) and Holly Frey (Full of Sith.)