First off, let me compliment for the general quality your ports have, despite you're relatively new to porting.
I gave a listen to all of them, here's what I can say:
Wario Land: Shake It! - Stonecarving City
This one isn't bad. Perhaps I'd lower #1's volume when it plays together with #0 using the @14s. I'd give a proper ADSR to the strings playing in #5 and #6, since you barely hear them, even with headphones on.
Lastly, maybe the main melody channels could benefit from Izun-echo
, try it out maybe.
Magical Astronomy - Satellite Café Terrace
Some feedback of the first applies here too: strings would sound better if they used a proper ADSR with very slow relase (something like $FA$E2). In the fastnotes part with all the @9, I'd suggest using something else for the channels that aren't supposed to use the same sample as the "main pianos". Saying this because there are sudden volume jumps, due to the fact sometimes the same note is played in more channels.
Lastly, a trick I feel like giving for your future percussion channels: ignore rests. Rather than @29c4 r8, always go for @29c4., since in the former case, it feels like the percussion gets cut midway while playing.
Aside all this, you're very brave, if you attempted this kind of port already looks at fastnotes...
And yes, echo can do wonders, so experiment more with it!
Copypaste what I said about ADSR. But overall, this song isn't too bad. Maybe, lower @4s' volumes, since they're kinda loud compared to the overall volume going of the song.
For all three songs:
you should try playing with panning (yXX). Panning can help making your song sound less mono.
Keep practicing, I look forward listening to your future ports!