I just checked Castlevania Chronicles (
KMCA-104~5) for a little bit. PS1 arrange is just as squashed on both but with a -0.30 dB limiter slapped in, X68000 original is louder in the Kuro boxset but the dynamics were kept mostly intact, and both CM-64/SC-55 are louder/more squashed and also feature the same -0.30 dB limiter. Amazon's digital release sounds closer to the original print to my ears.
As for Rondo of Blood, it seems the Kuro box uses the Dracula X Chronicles disc as source master, but yet again adds a -0.30 dB limiter that makes it louder/less dynamic and results in flat peaks (this also applies to
Morning Serenade, you can hear very audible clipping in both releases). Looking at your waveform for
Divine Bloodlines, 2010 boxset looks like a reprint of the Dracula X Chronicles master.
Curse of Darkness is also pretty flat/squashed in
GFCA-34~5. Most likely a reprint without major changes, as I suspected in my first reply.