Tiny "gaps" between objects using grid

[Iván Cardona]

When using the grid I've been noticing tiny gaps between objects that let you see the color of the object below, specially with an isometric grid and 0 gutter, is this something I should care about?

   

The size of the document is 11in x 17in these screenshots were taken at 630% zoom

To give some context, I'm making an illustration for a poster I'm going to print (300 dpi, CMYK) for a client. I'm a student with 2 years of experience using vector software.

When I turn on the pixel view mode or export to jpg at 100% quality I still see the gaps as pixels, and this is not the first time I notice them but I just ignored it and other times was solved extending the curves to cover the gap.

   

That basically solves the problem but I think it's unclean.

Here are some tests:
  

With vertical and horizontal lines can't be noticed

Here some yellow pixels appear visible through diagonal lines

  
In this one you can see the yellow gaps bellow almost every object connection in pixel view

So let's say there's a cleaner or clever solution for this, that would be great. But if there is not a solution, is this even important? At least for printing I don't know if this would be visible in the final product.

Edited September 19, 2020 by Iván Cardona
Making the point a little bit more clear

[Pšenda]

Try search Antialiasing problem.

For example this:

 

etc. 

[Iván Cardona]

15 hours ago, Pšenda said:

Try search Antialiasing problem.

For example this:

 

etc. 

I see, changing the coverage map works. This was very helpful and now I get that this is kind of a hard problem to solve and I hope someday this gets to be solved without any adjustments.
Thanks!