Did you check that it works in TUI? doom-lighten and doom-darken don't do anything to their argument when it's not in GUI

This is, how it looks like in vterm running inside a graphical emacs:

The next, when running vterm inside emacs -nw which runs inside another vterm.

So, you're right. It is only partially working. Suggestions?

I guess you can compute the colors that you like from GUI, and then hardcode the value in the theme, so you dodge the doom-darken/doom-lighten call.

You can evaluate (doom-lighten (doom-color 'red) 0.3) in a scratch buffer with the theme loaded to see the value (or use SPC h F to look at the faces and have the value directly there)

I fixed it (and some other things). First image shows vterm in GUI emacs:

Second image shows vterm in emacs -nw inside vterm:

This PR sort of grew to encompass issues that aren't related to the original one (plus the commit messages don't conform to our git conventions and there are issues with inheriting from faces that may not be available/loaded when they're used), so I've cherry picked bits into f5153a7 and 08d3d9b. That said, I'll investigate the other changes separately. Thanks for bringing these to my attention, in any case!