Another huge Shining Force 2 fan here! We did a little tribute a year ago on the forums & on Sega Mixer Drive on Radio Sega, you might want to check that out!
The sound of synths is actually very Mega Drive-y to me, many of the sounds seem very reminiscent of the original. Listening to the source & this arrangement back-to-back reveals more difference, but the palette isn't that far off. That's neither good or bad, it was just something that seemed like an interesting thing to me. The drumbeat adds a new element, since the original doesn't have any drums. It's not a very dominant element, but it does add something of a steady drive to the feel of the track. There's some subtle changes to bass line, and the rhythm of the sequencing, that also has this "steady drive" feel, whereas the original is kind of skipping and hopping a bit.
As far as OCR submission, two things stick out: first, this is very close to the original structurally, compositionally and even the genre and tone, apart from having drums, so I doubt it'll satisfy the "arrangement must be substantial and original" part of the submission standards. Second, structurally, he piece loops verbatim, or very close to it. It makes it feel less like a standalone track. (The fadeout at the end is also unsatisfying. I don't have an allergy to fadeouts, but it didn't feel like a good conclusion to the piece. But it's kinda moot point since the structure would need work anyhow.) Luckily, you can solve both these problems in one go by creatively rearranging the second go of the source material; original soloing, changeups of instrumentation & structure.. get creative with it, see what the composition inspires you to do.
One very specific feedback would be to make the intro bass notes longer, to give some more impact to the intro.
I thought that this was pretty well mixed: nothing seemed too quiet or loud to me, everything was audible and pleasant to listen to. I also liked the swooshing, reverby percussive/sfx sounds, they added a great deal of sense of space to the mix.