I think the specs on the Polish LG site are wrong. I'm not surprised because LG's websites are known for sometimes posting wrong/incorrect specs for drives. The US website shows two entirely conflicting sets of information for the 4167B - one claims it is a UDMA4 drive, the other UDMA2. One poor reader in this forum spent his time trying everything to get his 4167B to work as a UDMA4 device because of this (it is really a UDMA2 drive). Emailing LG just got him useless generic replies from some non-technical staff member who obviously has no idea what is going on. He ended up cursing and swearing in these forums in frustration.
Both the 4166B and the H20L use Panasonic chipsets. The characteristics of this chipset for burns are that it uses CAV for 16x burns, and Z-CLV for 8x burns starts at 4x before ramping speed to 8x. That is exactly what your graphs have shown for the burn of the TDK 8x disc above.
The 4167B uses a Renesas chipset. That is the drive which uses P-CAV for 16x burns. Z-CLV for 8x burns also goes from 6x to 8x as your second set of graphs show.
TYG01 is badly supported in firmware for the 4167B from DL11 onwards. This is a known fact many people have complained about and I verified it myself on my 4167B as well. TYG01 burned fine on DL10 but not on any version of firmware afterwards. Nobody is sure why exactly, but it only affects the 4167B. Btw, do not go looking for DL10, it only came with the first generation of 4167B writers and is not available for download.