can you set the sprite to check "overlaps at offset y+1 with vertical platform object", then deactivate gravity and directly set y to be the platform's y-height? Then just reactivate gravity when you jump. Don't have construct here, so can't confirm.
I tried an idea like that once too GMG, but it appeared to become very glitchy. So i can't really recommend something like that.
I have a little suggestion for you though: Deactivate the 'Center view on me' attribute of the player sprite. Instead put in the existing always event in the layout 2 sheet the following action:
System: Scroll to object player
This way it appears to work much better with the vibrating issues regarding the horizontal platform. It doesn't fix the issue with the vertical platform though. I just thought I'd mention it, also it's always a good idea to use events only for scrolling and never the 'Center view on me' attribute. In my opinion at least.
What I did in my project with vertical platform was, that I always added the difference of the Y position between ticks to the Y position of the player sprite, so it moved smoothly along with it instead of falling. That's how I'd roughly describe the method at least.