It's not getting translated probably because VIZ doesn't believe that they can make enough profit of it or because they think that putting their resources into publishing other mangas such as PokéSpe and the Pokémon movie mangas is more lucrative. And I say that's BS.
This manga fits VIZ's profile almost perfectly: multiple volumes and a fan favourite. What might be an unattractive factor for VIZ is that this is an original Pokémon manga (bulbapedia.bulbagarden.net/wiki/Pok%C3%A9mon_manga#Original_stories), meaning that it's not based on the games or the anime. The games' and anime's popularity increases the manga sales. This manga has support from neither the games nor the anime meaning that its sales might be lower than Pokémon mangas that are based on the games or anime.
Then it's also the fact that the anime and Pokémon Adventures is stealing the spotlight from all other Pokémon mangas. Also, have anyone ever seen advertising for English Pokémon mangas that wasn't in a VIZ / Chuang Yi product. I haven't.
Kinokuniya sells all eight Japanese volumes on their website (kinokuniya.com) including their US website (kinokuniya.com/us/) and in their stores across the US (kinokuniya.com/us/index.php/fho003) and some other parts of the world.
Pokémon RéBURST vol. 1: kinokuniya.com/us/index.php/fbs003?common_param=9784091232007
Pokémon RéBURST vol. 2: kinokuniya.com/us/index.php/fbs003?common_param=9784091233370
Pokémon RéBURST vol. 3: kinokuniya.com/us/index.php/fbs003?common_param=9784091235374
Pokémon RéBURST vol. 4: kinokuniya.com/us/index.php/fbs003?common_param=9784091236494
Pokémon RéBURST vol. 5: kinokuniya.com/us/index.php/fbs003?common_param=9784091237057
Pokémon RéBURST vol. 6: kinokuniya.com/us/index.php/fbs003?common_param=9784091238108
Pokémon RéBURST vol. 7: kinokuniya.com/us/index.php/fbs003?common_param=9784091238870
Pokémon RéBURST vol. 8: kinokuniya.com/us/index.php/fbs003?common_param=9784091240071
Follow these steps to find a Japanese Pokémon manga on a Kinokuniya site:
1. Go to Bulbapedia's Pokémon manga article (bulbapedia.bulbagarden.net/wiki/Pok%C3%A9mon_manga). Choose the desired Pokémon manga and copy it's Japanese name. RéBURST's Japanese name is ポケットモンスターRéBURST.
2. Go to a Kinokuniya site (kinokuniya.com), paste it, choose "Japanese Books" and hit enter.
3. Done.