This is not something I keep track of currently, but painting with a rather broad brush, being a Criollo, it would tend toward having a lower cocoa butter content. That said, the observation and conclusion you are drawing from it isn’t necessarily accurate. From days gone by, when I did actually test the beans for cocoa butter content, it varied from 49-56%. Forastero, on average, had more, and Criollo. So where is the problem? It’s this. That small difference has very little effect on the viscosity of the base liquor. I’ve never noticed much of a difference as long as the fat content is above 40% (once you start adding ingredients).
So what is causing that thickness? Well, I say not to over roast the Peru, and I mention Conacado and accept a heavier roast. What I’d hazard to hypothesize is that the Peru was roasted lighter (maybe a touch too light?) and contained more moisture. And that can and will make a huge difference in the base viscosity. 1% moisture can radically increase how thick your chocolate is. It’s good to keep in mind when reading about light and heavy roasts, that in all cases it should be a full roast to make sure the moisture is properly driven off. And don’t forget to let them completely cool before grinding into liquor. Water continues to be let off for some time after roasting.
I had the bright idea once to use that residual heat to jump start my grinding process….and over and over ended up with a seized mess. Some time later, I sealed up some barely warm to the touch roasted beans (maybe 100F) and came back to find all sorts of condensation in the bag. Moisture! And the cause of my seizing. It’s why I generally recommend 6 hours cooling before processing at all. Let that moisture escape.
So, good observation, but most likely the wrong conclusion, but good for the data you had on hand. I’m glad you asked.