As for the story and cast. I know the Dev has ideas for prequel and other story arcs potentially. I think the cast backstory being a bit "thin" makes sense in line with the actual plot. I suppose there could be more inter-team interaction to build off, but I feel I do have a general idea of personality of each person.
I found a few areas I could get out of bounds, but they weren't game breaking. Reported to dev.
I don't remember doing too many repeats of areas, but I like to explore around anyway so I didn't see a need for fast travel in the game.
I did find myself using the Energy attacks for most encounters, but I had a few to choose, single vs multi enemy attacks, so it gave me variety and allowed me to try different attack styles which was welcome.
Overall took about 6 1/2 - 7 hours to complete the game for me. I think the parallel story lines really were great and definitely agree that story progression felt good, I didn't feel overwhelmed with everything happening at once, but still didn't feel like I needed story faster either.
The first RPG Maker game I think I've finished so far, so for sure I'd recommend this to play.