Tralfamadore is actually not only one fictitious planet. It is, in addition to in Slaughterhouse Five, as mentioned, also mentioned in The Sirens of Titan by the same author, and is there quite different from how it is described in SH-5.
Naturally, as the Tralfamadorians in SH-5 can move around in 4-d, it is possible that they come from a later time on Tralfamadore than the one Salo from The Sirens of Titan is from. But asuming this is not so, the two 'Tralfamadores' are quite different planets.
In The Sirens of Titan Tralfamadore is habited by robots who built up civilization on Earth in order to ship a spare part to Salo's space ship on Titan. The Tralfamadorians in SH-5 are the aforementioned organic, time traveling, aliens.