Hello, I have some suggestions and opinions based on playing your maps.
[General]
- The black borders at the side of the BG look bad. Can you find a better one?
- Brown combo colour is really hard to read with the BG (if people dl with no video it's a problem). Please change it to colour that doesn't blend in with the BG
- The difficulty gap between Easy and Normal is quite big, and the difficulty gap between Normal and Hard is even bigger. You might want to make Easy harder and Hard easier to have a better spread.
[Easy]
00:54:426 (4) - It makes more sense to start this at 00:54:251 and end it because it's where the vocal and guitar start.
02:12:565 (3) - ^ new player would try to follow vocal. You could always have a gap here but the 1/1 will be confusing.
03:27:914 (1,2,3) - Add more notes / sliders here. The huge gap between notes can be hard to follow.
[Normal]
00:43:961 (4) - Delete? It'll be hard for a newer player to catch this because it's not following anything obvious.
01:04:193 (5) - Clap the return
01:17:449 (6) - This overlap is bad. Maybe remove a return on 01:16:577 (5) - then create a note + slider?
02:34:891 (6) - Delete and add a return to 02:33:495 (5) - ?
02:53:379 (1) - Why not delete this and end the spinner here instead? Also I think the clap is too loud here.
02:56:344 (2) - Delete? Make it easier and it looks nicer.
03:31:402 (4) - Same thing I said about 01:17:449 (6) - the overlap is bad and I think would be better with note and slider.
[NNastice's Taiko]
02:01:402 (1) - Extend to 02:02:798 ?
[Collab Hard]
- I think the custom finish is too heavy for this song, maybe reduce the volume on it a bit.
00:31:926 (5) - Silenced slider ends are unrankable now apparently. Increase the volume and make it soft hitsound?
01:03:495 (4,5,1,2) - Make it easier. This pattern is more of an Insane? In fact you did almost exactly the same thing in insane with smaller jumps 02:00:356 (4,5,6,7) -
01:13:961 (4) - New combo to show spacing change here?
01:29:833 (2,3) - Remove the jump? I think it's better if you keep the spacing the same as everything else in this section 01:30:705 (1,2,3,4) - etc
01:58:612 (1) - Remove clap from the end.
01:59:135 (2) - ^
02:59:658 (3,1,2,3,4,1,2,3,4,5,6) - So cluttered, I think it'd play better with this SV if you made the rhythm more simple.
03:05:414 (1,1) - New combos really necessary?
This feels like an Easy Insane but not a Hard. I'm reluctant to suggest to make things easier because it's good but calling it a Hard is mislabelling imo.
[Collab Insane]
- Too much triple spam, just sounds out of place
00:47:449 (1) - Jump doesn't make much sense, compare to 00:50:065 (4,1) -
00:55:821 - Why is this a x1.20 section? The other kiai time doesn't use a speedup. Some things about collabs should be consistent and this is one of them imo.
01:03:321 (3,4,5) - Why the jump? Everytime I play it, it just doesn't make sense.
01:05:588 (1,2,3,4,5,6,7,8,9,10,11,12,13) - It sounds bad and is completely random. The guitar is the most prominent part but you map over it with a stream? It'd be better if you followed the music.
01:46:228 (3) - Slider-end is covered by the previous hitburst. Maybe move the position of 01:45:705 (3) -
02:00:705 (5) - You should try to make this more visible with a new combo or something.
02:03:147 - 02:08:030 - Whistle is too loud it's unfitting. I'd say 50-60% is good for this part.
02:13:088 (3,4,5,6,7,8,9,10,11,1) - I found it funny you ignored the guitar that is on 1/4 at 02:13:176 but then decided to throw in a stream that doesn't follow anything. Again following the guitar would be better.
02:34:891 (1,2,3,4) - This sounds weird. Follow the music more and remove the custom hitsounds? Or you could just start the break here I suppose.
02:57:827 (8) - Delete? You're supposed to be following the guitar?
03:01:751 (2) - Spacing, space it like the rest of the 1/4 in the map.
03:16:054 (8,9,10,1) - Somewhat confusing spacing. I think it would be better if you moved 03:16:228 (9) - somewhere else and kept the same spacing between 03:16:402 (10,1) -
03:19:542 (1) - Is the new combo really necessary?
03:19:891 (1) - ^
Hmm there are some very good ideas in this diff but it doesn't feel cohesive, like the first kiai is much harder than the last and they flow differently etc. Also it feels overmapped at times with all the triples.
That's all from me, overall I think the spread could be improved and some of the overmapping in Insane cut. Maybe get some more mods or another MAT and see what they think.
eikkaleyd~
and sorry for arriving late due to some irl business and some other stuff... sorry about that. 
you can leave it, but i would remove nc.