Here’s a diff with a few fixes to the issues you mentioned:
(I only applied them to the first two charts, hopefully you can see what to do for the rest.)
the y axis text is not displayed,
This is because you were missing some required attributes on the text element, namely the x attribute and the fill (or stroke) attribute. This aside, the axis labels were being drawn outside the SVG, which I solved by setting overflow: visible. There are also other ways to fix this, see the examples in the forum post below.
y axis is upside down.
Your function for the cy attribute was reversed (recall that y=0 is the top of the image, and y=height is the bottom). I changed the cx and cy functions to use the x and y scales that you already defined.
This recent forum post has some more resources for axes in D3 charts on Observable: