According to some here, a lot of the WWI plane's FM are sort of frankenplane derivatives. So it could be just the FM.
I've had some experience with other WWI flight sims FM and the Roland is a strange beast. In CFS3-WOFF it's way too ubered and manuverable, flying similar to an oversized Fokker DVII. A DH2 hardly has a chance against a Roland CII in OFF, where historically they're actually fairly well matched with an edge in maneuverability to the Airco, but it giving up some speed to the more powerful engine of the Roland
The Roland should have a bit of wing area lift efficiency loss due to it's biplane wings being too close together. it's somewhat aerodynamically clean but the fuselage is really tall and has a fair bit of frontal area, so it has two negatives from induced drag loss and slightly more frontal area drag.
I have some issues with a lot of these IL-2 WWI planes. The biggy with me is that the rotary engines all torque and P effect backwards to normal left hand turning ( viewed from the front..) rotaries. The other is the insane amount of propeller inertia and gyroscopic procession. The Neiuport 10 series seem to be the worst of this group, but the N11, 17 and 20 series, most of the Sopwiths, also take wa-ay too long to spool up to full RPM.
If I knew how to work on these FM's I'd tackle trying to adjust them, apparently you need to know Java to fix them.