Indigo Night

Simple piece with piano + flute part playing 7 against 8, and a middle solo flute section using additive and changing rhythms and Messiaen's mode 5 in several transpositions.

https://soundcloud.com/user-417172164/indigo-night

I think you may think this sounds a little more homogenous than it actually is because your program performs the 7 against 8 when the flute has the melody incorrectly, having the flute sometimes latch onto the final four notes of any given measure.
The flute cadenza is the downfall of this piece for my ears. I think you could have easily done more polyphony with the piano, exploring added values instead of this... it just sounds so much like Boulez, and not like Messeian there. 
The rest of the piece is really quite nice!

EDIT: It's my understanding you don't need it to "sound like Messeian there", but what I meant was that it was out of character to the rest of a rhythmic and harmonic idea.

Thank you.

It must be a matter of perception. I can distinctly hear the 7 and the 8 separatedly. The difference is very short, that's the intention. At least, the software thinks in maths. I've never had problems with polyrhythm with Finale.

I didn't want to sound like Messiaen (it would be impossible!). I only use one of his modes here.

Barber used 7 against 8, for example.

I don't have a gripe with the rhythms as they're written, or how they would normally sound. I want to emphasize I clearly hear the distinct rhythms when the piano is in 7, but not the flute. Maybe it's just the envelope of the flute. 

OK, I agree with that.

I think that, perhaps, it's because the part with the piano in 7 is much more percussive.

(I thought my Finale was wrong... ). Thanks for the clear observation.

(I'm taking a nice course in contemporary composition and it's wonderful but everything goes very fast and I have not time enough to write longer or structured pieces... When it finishes there'll be time. But I love learning this stuff!).

This feels like two separate pieces. The rhythmic language of the flute cadenza is so different from the rest of the piece that I don't sense a thread unifying the piece.

As for the rhythmic discrepancy in the flute, I am hearing them as not entirely even. Maybe human playback is applying some rubato?