for the most part id rather not understand death metal. especially brutal death
.
tho some bands like later death, athiest, some suffocation, decapitated, and nile dont have lyrics totally based around gore so it might be nice to understand them more easily.
for the most part i dont need to hear cannibal corpse lyrics for an example. I have the general idea of what is going on I Cum Blood.
as for CC's newer stuff the lyrics are somewhat of better quality and understanding them while listening may be worth it. I have read all the lyrics but i dont think hearing them or not would much effect my listening experience.