Kinda sounds like it needed a performant reimplementation, period. This is what the game looks like. There's just a flat isometric plane of squares with animated sprites in it.

https://youtu.be/OBsRPhCm5sU?t=899

The Vita and the PSP both have a lot of tactical RPGs that are a lot higher in complexity, with actual 3D environments as well as randomly generated ones (much harder to handle than pre-made hard-coded ones).

Compare with best-in-class on that platform: https://youtu.be/nUhspS9VddQ?t=3539