Evening, @Elle,
Now, that paragraph of yours calls for weeks of clever thinking as well as umpteen new experiments…
a) I use cheapish paper chiefly because it is more challenging 
Those experiments will teach me more: it is dead easy to make a good print on super-glossy-whatever. But take newsprint, for example. Now, that is a challenge!
b) I do not agree that ancient palettes were limited. You should see the list of pigments that were available to the ancient Egyptians, for instance. Or How to Paint a Mammoth when dirts (i.e. earth colours) were all that were at hand.
c) van Eyck was one of the first attributed to making glazes in oil, but the method was well known among those working with egg tempera long before that.
In short, glazes (or rather overpainting with a thin layer) in tempera work in this way:
Imagine that you have two cups of paint. They are both blue, but one is slightly lighter (L) than the one in the other cup (D).
- a thin D layer on top of an L layer = a glaze, which will look transparent.
- a thin D layer on top of an D layer = a solid, which will yield opacity.
- a thin L layer on top of an D layer = a scumble, which will yield opalescence.
I know far too little about Krita, but does this not sound as if this glaze/solid/scumble ought to fit in well there?
Have fun!
Claes in Lund, Sweden