The drawings on this site come from the ROM, not from the emulator. But looking at a picture is not enough to believe it: in this series the VRAM is dumped from openMSX and compared byte for byte against what the Python builds. If they match, the format has been read correctly.
openmsx -machine Philips_VG_8020 -cart skyjaguar.romtools/ holds openMSX TCL scripts meant for checking, not for illustrating: they dump the 16 KB of VRAM and the VDP registers and exit on their own, with a real-time watchdog so a broken script cannot leave the emulator hanging.
Two things learned the hard way, in case you write your own: in TCL do not nest quotes inside a string (use {VDP regs}), and do not set breakpoints that fire every frame inside drawing routines — they choke the emulator, which then never even gets a game started.