I have been checking a prototype version of Zero Mission that contained a sound debug mode with all the music, and the tracks appeared in this order (names are mostly unofficial as no soundtrack release exists for this game):
At a glance, it looks like the tracks are mostly grouped together in two specific groups, specifically 01-28 and 50-84. While this may very well mean nothing, and we have nothing outright confirmed as a base, I have a theory that 01-28 were done by Kenji Yamamoto, while 50-84 were by Minako Hamano; based on their known works from various other Metroid and Nintendo titles, they line well with their instrumentation, styles, etc. It kinda looks like they probably had their own tracks grouped together when they were implementing the music on the game.
(By the way, this has nothing to do with the unlockable sound test in the final game, as it is incomplete and has a completely different track order)