Still no official confirmation but I could bet my life on this lol : we have
more Go Ichinose for Legends (the second music references "Battle! (Wild Pokémon)" from Diamond and Pearl, that's so cool!),
and some Hitomi Sato too!!
We also had
this music on this small video posted a while ago, most likely composed by Sato too.
It's nice to see the two main composers from DP return for Legends!