When playing the new build, there was a few problems I had with the controls. Some of them are reoccurring issues from the last build, while others might just be glitches or settings exclusive to the keyboard. I've only played on keyboard, and coming from RoA, it feels like they're missing a few settings.

1. The attack button doesn't work if I'm holding jump + a direction. Edit: Up is not counted as a direction. Guess its a side effect from #2.

I have no idea why this happens. I assume it is just a bug, but its so consistent that it feels intentional. The c stick buttons work just fine, so its not to prevent full jump aerials.

2. Up + left/right doesn't do up air

This was in the last build as well, and it annoys me so much. I assume this is for people who use tap jump, but as someone who doesn't, I'd at least like the option to turn this off. In the same scenario, the special button does up special, so its not even consistent.

3. Down + left/right doesn't do down air. Only on Mega Man. Only when using it out of his recovery.

I still don't understand this one either. When down air gave height, I suicided so many times when trying to grab the ledge. Every other time, it does down air. Why does this do forward air?

4. Dash + up smash does up tilt

This one's pretty strange. While it is useful, and I already used Cactuar dashing to use down smash while approaching, I'm not sure why they removed this. I can do it as normal with the c stick buttons. It also requires a slight delay to do it out of a walk, but dashing has failed every time.

5. Dash + down on a ledge no longer makes you fall through the ledge

I'm kind of mixed on this one. On one hand, it makes Cactuar dashing on ledges much easier, which I like, but at the same time there's no longer a quick way to fall through ledges. I am glad that it shield drops on ledges though.

Edit: 6. Neutral specials cannot be reversed

Up specials can be reversed. Down specials can be reversed. Why can't neutral specials?

With tap jump it works because you never need to hit the jump button; this only happens specifically when holding the jump button. It might happen if you have that set on your control scheme.

Edit: Full jump aerials are common on stages with platforms; RAR bair is one of my main approaches to someone camping on a ledge. Up tilt combos also aren't conveniently in place for a short hop every time.

There's no such thing as a dash button in Melee; in other games moving the controller halfway let you do an attack and all the way had you go through. Also, having to double tap is two inputs, which eats up about 4 extra frames. The dash + down in RoA and .9b let you do it in one input.

I also forgot one; it is impossible to b reverse neutral special.

No, I was using a jump button, not pressing up, but I hadn't turned off tap jump, and that might have changed things.
RAR bair isn't super immediate, is it? As long as it isn't a super low platform, tap jumpers have plenty of time to let go of up.
B-reverse isn't in this game. You can turnaround B instead, where you press the direction and let go before pressing B. You can't reverse up/down B either, because you press the direction before or at the same time as B. In melee, you can turn around during an up B, which is why the european Ken combo isn't possible in ssf2.

Maybe its a glitch on Mac; I tried with tap jump on and it still happened.

Also, floating. Nair and Uair aren't the only aerials Goku and Peach want to use when floating.

Yes, you can reverse down specials. I've done it frequently. Pick any character that's not falcon, use down special, then quickly hit the opposite direction while in the air. You turn around in mid air. Neutral specials cannot turn around in mid air. This is really annoying because every single bair into neutral special combo on every character is now impossible. Landing and turning around takes a lot of frames, especially for floaty characters who could otherwise combo.

This is impossible for me to do: Down b, then in a later frame, reverse direction.
This is possible for me: Hold the reverse direction before or on the same frame as down b to do it facing the other way.
I realize this is annoyingly pedantic, but ssb4 and maybe brawl have B reversing which affects your momentum, while this does not.

What combo with what characters are you talking about? If you need the momentum switching properties of ssb4, you're out of luck. If not, you can turnaround B.
As far as I know, this is exactly the same as how melee does it. The timing is pretty tight.

Edit: Marth's up B is one example of how you can't reverse up B, since you can't tipper someone then up B the other way. Falcon's down B is another: you can't zig zag with it. Or Ichigo's down B: pressing back after starting the move makes him pull back, which would be impossible if the move was truly reversable.

I don't mean momentum, just using the move in the other direction. I have no problem reversing marth's up special, or Pac-Man's down special (Captain Falcon and similar down specials cannot reverse even in smash 4), but I spent ages labbing in .9b trying to reverse neutral specials. As far as I can see, there's no timing to it, its just impossible. I haven't found the timing for reversing up or down specials difficult at all, and don't see how neutral special could have such a stricter timing.

The combo I was trying to do was Bandana Dee's ffbair into neutral special. Or even neutral special after they DI behind behind me from a ffnair. I have never seen a neutral special that could be turned around. That's why I specified neutral special, not up or down specials which are the only examples you've given.

Proof: https://youtu.be/v5TsJeLB93M

Press a direction. As fast as you can, let go and press B. If you get a side B, you went to fast. If you didn't turn around, you went to slowly.