Or tales-of-maj-eyal. I don't know exactly what we do with apostrophes.
The game name is Tales of Maj'Eyal. This is how it appears on Steam. Tome-4 is not a terrible tag for people familiar with the development of the game, but for newbies who pick it up on Steam and google for an answer, they're going to be googling "Tales of Maj'Eyal", not "Tome4".
We should at the very least add that alias, if not simply rename the tag and make tome-4 the alias.