OK, time for a list I've compiled of music missing from the OST prints. Yes, even with 5 discs of BGM from a 30-hour NDS RPG, there's still missing music...
(spoilers ahead)
1. Opening theme, composed & arranged by Jun Sasaki as confirmed by the ending credits; see
http://vgmdb.net/album/10716
2. BGM that plays during the Order's siege on the player's fortress
3. BGM when plains appear in place of Ch'olui Mountains; uses Furious Roar theme; composed by Yoshino Aoki
4. BGM when Diulf touches the Furiour Roar artifact; composed by Yoshino Aoki
5. BGM when meeting Guntram for the first time; composed by Masaharu Iwata
6. an ominous theme... I should have kept better notes on it, but it has something to do with Janam.
7. BGM that plays during the appearance of the desert