An addendum on the subject of the VT03 palette:
I noticed that Pic32, V.R. Technology's official graphics drawing utility, comes with two palette files: HSL_NTSC.TAB and HSL_PAL.TAB. EmuVT's hard-coded palette matches HSL_PAL.TAB, but the DGUN-2573 220-in-1 plug-and-play console's games' 12-bit RGB colors are close matches of HSL_NTSC.TAB. This indicates that for most VT03 games, HSL_NTSC.TAB represents the authors' intent, and EmuVT's palette is quite off. This is most visible in Curly Monkey 2, where on the title screen, the monkey is magenta rather than red in EmuVT when using the DGUN-2500 130-in-1 multicart. HSL_NTSC.TAB is also somewhat darker than EmuVT/HSL_PAL.TAB, and I have always thought that EmuVT's palette was a bit too bright. Compare (left: VT3x RGB, middle: HSL_NTSC.TAB, right: HSL_PAL.TAB/EmuVT):
In other words: I wasted my time trying to approximate EmuVT's palette in my palette generation code, because that's not the correct palette that needs to be approximated.